# “Named” Permutation groups (such as the symmetric group, S_n)¶

You can construct the following permutation groups:

– SymmetricGroup, $$S_n$$ of order $$n!$$ (n can also be a list $$X$$ of distinct
positive integers, in which case it returns $S_X$)
– AlternatingGroup, $$A_n$$ or order $$n!/2$$ (n can also be a list $$X$$
of distinct positive integers, in which case it returns $A_X$)

– DihedralGroup, $$D_n$$ of order $$2n$$

– GeneralDihedralGroup, $$Dih(G)$$, where G is an abelian group

– CyclicPermutationGroup, $$C_n$$ of order $$n$$

– DiCyclicGroup, nonabelian groups of order $$4m$$ with a unique element of order 2

– TransitiveGroup, $$n^{th}$$ transitive group of degree $$d$$
from the GAP tables of transitive groups (requires the “optional” package database_gap)

– TransitiveGroups(d), TransitiveGroups(), set of all of the above

– PrimitiveGroup, $$n^{th}$$ primitive group of degree $$d$$
from the GAP tables of primitive groups (requires the “optional” package database_gap)

– PrimitiveGroups(d), PrimitiveGroups(), set of all of the above

– MathieuGroup(degree), Mathieu group of degree 9, 10, 11, 12, 21, 22, 23, or 24.

– KleinFourGroup, subgroup of $$S_4$$ of order $$4$$ which is not $$C_2 \times C_2$$

– QuaternionGroup, non-abelian group of order $$8$$, $$\{\pm 1, \pm I, \pm J, \pm K\}$$

– SplitMetacyclicGroup, nonabelian groups of order $$p^m$$ with cyclic subgroups of index p

– SemidihedralGroup, nonabelian 2-groups with cyclic subgroups of index 2

– PGL(n,q), projective general linear group of $$n\times n$$ matrices over
the finite field GF(q)
– PSL(n,q), projective special linear group of $$n\times n$$ matrices over
the finite field GF(q)
– PSp(2n,q), projective symplectic linear group of $$2n\times 2n$$ matrices
over the finite field GF(q)
– PSU(n,q), projective special unitary group of $$n \times n$$ matrices having
coefficients in the finite field $GF(q^2)$ that respect a fixed nondegenerate sesquilinear form, of determinant 1.
– PGU(n,q), projective general unitary group of $$n\times n$$ matrices having
coefficients in the finite field $GF(q^2)$ that respect a fixed nondegenerate sesquilinear form, modulo the centre.

– SuzukiGroup(q), Suzuki group over GF(q), $$^2 B_2(2^{2k+1}) = Sz(2^{2k+1})$$.

AUTHOR:
• David Joyner (2007-06): split from permgp.py (suggested by Nick Alexander)
REFERENCES:
Cameron, P., Permutation Groups. New York: Cambridge University Press, 1999. Wielandt, H., Finite Permutation Groups. New York: Academic Press, 1964. Dixon, J. and Mortimer, B., Permutation Groups, Springer-Verlag, Berlin/New York, 1996.
NOTE:
Though Suzuki groups are okay, Ree groups should not be wrapped as permutation groups - the construction is too slow - unless (for small values or the parameter) they are made using explicit generators.
class sage.groups.perm_gps.permgroup_named.AlternatingGroup(domain=None)

The alternating group of order $$n!/2$$, as a permutation group.

INPUT:

n – a positive integer, or list or tuple thereof

Note

This group is also available via groups.permutation.Alternating().

EXAMPLES:

sage: G = AlternatingGroup(6)
sage: G.order()
360
sage: G
Alternating group of order 6!/2 as a permutation group
sage: G.category()
Category of finite permutation groups
sage: TestSuite(G).run() # long time

sage: G = AlternatingGroup([1,2,4,5])
sage: G
Alternating group of order 4!/2 as a permutation group
sage: G.domain()
{1, 2, 4, 5}
sage: G.category()
Category of finite permutation groups
sage: TestSuite(G).run()


TESTS:

sage: groups.permutation.Alternating(6)
Alternating group of order 6!/2 as a permutation group

class sage.groups.perm_gps.permgroup_named.CyclicPermutationGroup(n)

A cyclic group of order n, as a permutation group.

INPUT:
n – a positive integer

Note

This group is also available via groups.permutation.Cyclic().

EXAMPLES:

sage: G = CyclicPermutationGroup(8)
sage: G.order()
8
sage: G
Cyclic group of order 8 as a permutation group
sage: G.category()
Category of finite permutation groups
sage: TestSuite(G).run()
sage: C = CyclicPermutationGroup(10)
sage: C.is_abelian()
True
sage: C = CyclicPermutationGroup(10)
sage: C.as_AbelianGroup()
Multiplicative Abelian group isomorphic to C2 x C5


TESTS:

sage: groups.permutation.Cyclic(6)
Cyclic group of order 6 as a permutation group

as_AbelianGroup()

Returns the corresponding Abelian Group instance.

EXAMPLES:

sage: C = CyclicPermutationGroup(8)
sage: C.as_AbelianGroup()
Multiplicative Abelian group isomorphic to C8

is_abelian()

Return True if this group is abelian.

EXAMPLES:

sage: C = CyclicPermutationGroup(8)
sage: C.is_abelian()
True

is_commutative()

Return True if this group is commutative.

EXAMPLES:

sage: C = CyclicPermutationGroup(8)
sage: C.is_commutative()
True

class sage.groups.perm_gps.permgroup_named.DiCyclicGroup(n)

The dicyclic group of order $$4n$$, for $$n\geq 2$$.

INPUT:
• n – a positive integer, two or greater

OUTPUT:

This is a nonabelian group similar in some respects to the dihedral group of the same order, but with far fewer elements of order 2 (it has just one). The permutation representation constructed here is based on the presentation

$\langle a, x\mid a^{2n}=1, x^{2}=a^{n}, x^{-1}ax=a^{-1}\rangle$

For $$n=2$$ this is the group of quaternions ($${\pm 1, \pm I,\pm J, \pm K}$$), which is the nonabelian group of order 8 that is not the dihedral group $$D_4$$, the symmetries of a square. For $$n=3$$ this is the nonabelian group of order 12 that is not the dihedral group $$D_6$$ nor the alternating group $$A_4$$. This group of order 12 is also the semi-direct product of of $$C_2$$ by $$C_4$$, $$C_3\rtimes C_4$$. [CONRAD2009]

When the order of the group is a power of 2 it is known as a “generalized quaternion group.”

IMPLEMENTATION:

The presentation above means every element can be written as $$a^{i}x^{j}$$ with $$0\leq i<2n$$, $$j=0,1$$. We code $$a^i$$ as the symbol $$i+1$$ and code $$a^{i}x$$ as the symbol $$2n+i+1$$. The two generators are then represented using a left regular representation.

Note

This group is also available via groups.permutation.DiCyclic().

EXAMPLES:

A dicyclic group of order 384, with a large power of 2 as a divisor:

sage: n = 3*2^5
sage: G = DiCyclicGroup(n)
sage: G.order()
384
sage: a = G.gen(0)
sage: x = G.gen(1)
sage: a^(2*n)
()
sage: a^n==x^2
True
sage: x^-1*a*x==a^-1
True


A large generalized quaternion group (order is a power of 2):

sage: n = 2^10
sage: G=DiCyclicGroup(n)
sage: G.order()
4096
sage: a = G.gen(0)
sage: x = G.gen(1)
sage: a^(2*n)
()
sage: a^n==x^2
True
sage: x^-1*a*x==a^-1
True


Just like the dihedral group, the dicyclic group has an element whose order is half the order of the group. Unlike the dihedral group, the dicyclic group has only one element of order 2. Like the dihedral groups of even order, the center of the dicyclic group is a subgroup of order 2 (thus has the unique element of order 2 as its non-identity element).

sage: G=DiCyclicGroup(3*5*4)
sage: G.order()
240
sage: two = [g for g in G if g.order()==2]; two
[(1,5)(2,6)(3,7)(4,8)(9,13)(10,14)(11,15)(12,16)]
sage: G.center().order()
2


For small orders, we check this is really a group we do not have in Sage otherwise.

sage: G = DiCyclicGroup(2)
sage: H = DihedralGroup(4)
sage: G.is_isomorphic(H)
False
sage: G = DiCyclicGroup(3)
sage: H = DihedralGroup(6)
sage: K = AlternatingGroup(6)
sage: G.is_isomorphic(H) or G.is_isomorphic(K)
False


TESTS:

sage: groups.permutation.DiCyclic(6)
Diyclic group of order 24 as a permutation group


REFERENCES:

AUTHOR:
• Rob Beezer (2009-10-18)
is_abelian()

Return True if this group is abelian.

EXAMPLES:

sage: D = DiCyclicGroup(12)
sage: D.is_abelian()
False

is_commutative()

Return True if this group is commutative.

EXAMPLES:

sage: D = DiCyclicGroup(12)
sage: D.is_commutative()
False

class sage.groups.perm_gps.permgroup_named.DihedralGroup(n)

The Dihedral group of order $$2n$$ for any integer $$n\geq 1$$.

INPUT:
n – a positive integer
OUTPUT:
– the dihedral group of order 2*n, as a permutation group

Note

This group is also available via groups.permutation.Dihedral().

EXAMPLES:

sage: DihedralGroup(1)
Dihedral group of order 2 as a permutation group

sage: DihedralGroup(2)
Dihedral group of order 4 as a permutation group
sage: DihedralGroup(2).gens()
[(3,4), (1,2)]

sage: DihedralGroup(5).gens()
[(1,2,3,4,5), (1,5)(2,4)]
sage: list(DihedralGroup(5))
[(), (2,5)(3,4), (1,2)(3,5), (1,2,3,4,5), (1,3)(4,5), (1,3,5,2,4), (1,4)(2,3), (1,4,2,5,3), (1,5,4,3,2), (1,5)(2,4)]

sage: G = DihedralGroup(6)
sage: G.order()
12
sage: G = DihedralGroup(5)
sage: G.order()
10
sage: G
Dihedral group of order 10 as a permutation group
sage: G.gens()
[(1,2,3,4,5), (1,5)(2,4)]

sage: DihedralGroup(0)
Traceback (most recent call last):
...
ValueError: n must be positive


TESTS:

sage: TestSuite(G).run()
sage: G.category()
Category of finite permutation groups
sage: TestSuite(G).run()

sage: groups.permutation.Dihedral(6)
Dihedral group of order 12 as a permutation group

class sage.groups.perm_gps.permgroup_named.GeneralDihedralGroup(factors)

The Generalized Dihedral Group generated by the abelian group with direct factors in the input list.

INPUT:

• factors - a list of the sizes of the cyclic factors of the abelian group being dihedralized (this will be sorted once entered)

OUTPUT:

For a given abelian group (noting that each finite abelian group can be represented as the direct product of cyclic groups), the General Dihedral Group it generates is simply the semi-direct product of the given group with $$C_2$$, where the nonidentity element of $$C_2$$ acts on the abelian group by turning each element into its inverse. In this implementation, each input abelian group will be standardized so as to act on a minimal amount of letters. This will be done by breaking the direct factors into products of p-groups, before this new set of factors is ordered from smallest to largest for complete standardization. Note that the generalized dihedral group corresponding to a cyclic group, $$C_n$$, is simply the dihedral group $$D_n$$.

EXAMPLES:

As is noted in [1], $$Dih(C_3 \times C_3)$$ has the presentation

$\langle a, b, c\mid a^{3}, b^{3}, c^{2}, ab = ba, ac = ca^{-1}, bc = cb^{-1} \rangle$

Note also the fact, verified by [1], that the dihedralization of $$C_3 \times C_3$$ is the only nonabelian group of order 18 with no element of order 6.

sage: G = GeneralDihedralGroup([3,3])
sage: G
Generalized dihedral group generated by C3 x C3
sage: G.order()
18
sage: G.gens()
[(4,5,6), (2,3)(5,6), (1,2,3)]
sage: a = G.gens()[2]; b = G.gens()[0]; c = G.gens()[1]
sage: a.order() == 3, b.order() == 3, c.order() == 2
(True, True, True)
sage: a*b == b*a, a*c == c*a.inverse(), b*c == c*b.inverse()
(True, True, True)
sage: G.subgroup([a,b,c]) == G
True
sage: G.is_abelian()
False
sage: all([x.order() != 6 for x in G])
True


If all of the direct factors are $$C_2$$, then the action turning each element into its inverse is trivial, and the semi-direct product becomes a direct product.

sage: G = GeneralDihedralGroup([2,2,2])
sage: G.order()
16
sage: G.gens()
[(7,8), (5,6), (3,4), (1,2)]
sage: G.is_abelian()
True
sage: H = KleinFourGroup()
sage: G.is_isomorphic(H.direct_product(H)[0])
True


If two nonidentical input lists generate isomorphic abelian groups, then they will generate identical groups (with each direct factor broken up into its prime factors), but they will still have distinct descriptions. Note that If $$gcd(n,m)=1$$, then $$C_n \times C_m \cong C_{nm}$$, while the general dihedral groups generated by isomorphic abelian groups should be themselves isomorphic.

sage: G = GeneralDihedralGroup([6,34,46,14])
sage: H = GeneralDihedralGroup([7,17,3,46,2,2,2])
sage: G == H, G.gens() == H.gens()
(True, True)
sage: [x.order() for x in G.gens()]
[23, 17, 7, 2, 3, 2, 2, 2, 2]
sage: G
Generalized dihedral group generated by C6 x C34 x C46 x C14
sage: H
Generalized dihedral group generated by C7 x C17 x C3 x C46 x C2 x C2 x C2


A cyclic input yields a Classical Dihedral Group.

sage: G = GeneralDihedralGroup([6])
sage: D = DihedralGroup(6)
sage: G.is_isomorphic(D)
True


A Generalized Dihedral Group will always have size twice the underlying group, be solvable (as it has an abelian subgroup with index 2), and, unless the underlying group is of the form $${C_2}^n$$, be nonabelian (by the structure theorem of finite abelian groups and the fact that a semi-direct product is a direct product only when the underlying action is trivial).

sage: G = GeneralDihedralGroup([6,18,33,60])
sage: (6*18*33*60)*2
427680
sage: G.order()
427680
sage: G.is_solvable()
True
sage: G.is_abelian()
False


TESTS:

sage: G = GeneralDihedralGroup("foobar")
Traceback (most recent call last):
...
TypeError: factors of abelian group must be a list, not foobar

sage: GeneralDihedralGroup([])
Traceback (most recent call last):
...
ValueError: there must be at least one direct factor in the abelian group being dihedralized

sage: GeneralDihedralGroup([3, 1.5])
Traceback (most recent call last):
...
TypeError: the input list must consist of Integers

sage: GeneralDihedralGroup([4, -8])
Traceback (most recent call last):
...
ValueError: all direct factors must be greater than 1


REFERENCES:

 [1] A.D. Thomas and G.V. Wood, Group Tables (Exeter: Shiva Publishing, 1980)

AUTHOR:

• Kevin Halasz (2012-7-12)
class sage.groups.perm_gps.permgroup_named.KleinFourGroup

The Klein 4 Group, which has order $$4$$ and exponent $$2$$, viewed as a subgroup of $$S_4$$.

OUTPUT:
– the Klein 4 group of order 4, as a permutation group of degree 4.

Note

This group is also available via groups.permutation.KleinFour().

EXAMPLES:

sage: G = KleinFourGroup(); G
The Klein 4 group of order 4, as a permutation group
sage: list(G)
[(), (3,4), (1,2), (1,2)(3,4)]


TESTS:

sage: G.category()
Category of finite permutation groups
sage: TestSuite(G).run()

sage: groups.permutation.KleinFour()
The Klein 4 group of order 4, as a permutation group

AUTHOR:
– Bobby Moretti (2006-10)
class sage.groups.perm_gps.permgroup_named.MathieuGroup(n)

The Mathieu group of degree $$n$$.

INPUT:
n – a positive integer in {9, 10, 11, 12, 21, 22, 23, 24}.
OUTPUT:
– the Mathieu group of degree n, as a permutation group

Note

This group is also available via groups.permutation.Mathieu().

EXAMPLES:

sage: G = MathieuGroup(12)
sage: G
Mathieu group of degree 12 and order 95040 as a permutation group


TESTS:

sage: G.category()
Category of finite permutation groups
sage: TestSuite(G).run(skip=["_test_enumerated_set_contains", "_test_enumerated_set_iter_list"])

sage: groups.permutation.Mathieu(9)
Mathieu group of degree 9 and order 72 as a permutation group


Note: this is a fairly big group, so we skip some tests that currently require to list all the elements of the group, because there is no proper iterator yet.

class sage.groups.perm_gps.permgroup_named.PGL(n, q, name='a')

The projective general linear groups over GF(q).

INPUT:
n – positive integer; the degree q – prime power; the size of the ground field name – (default: ‘a’) variable name of indeterminate of finite field GF(q)
OUTPUT:
PGL(n,q)

Note

This group is also available via groups.permutation.PGL().

EXAMPLES:

sage: G = PGL(2,3); G
Permutation Group with generators [(3,4), (1,2,4)]
sage: print G
The projective general linear group of degree 2 over Finite Field of size 3
sage: G.base_ring()
Finite Field of size 3
sage: G.order()
24

sage: G = PGL(2, 9, 'b'); G
Permutation Group with generators [(3,10,9,8,4,7,6,5), (1,2,4)(5,6,8)(7,9,10)]
sage: G.base_ring()
Finite Field in b of size 3^2

sage: G.category()
Category of finite permutation groups
sage: TestSuite(G).run() # long time


TESTS:

sage: groups.permutation.PGL(2, 3)
Permutation Group with generators [(3,4), (1,2,4)]

class sage.groups.perm_gps.permgroup_named.PGU(n, q, name='a')

The projective general unitary groups over GF(q).

INPUT:
n – positive integer; the degree q – prime power; the size of the ground field name – (default: ‘a’) variable name of indeterminate of finite field GF(q)
OUTPUT:
PGU(n,q)

Note

This group is also available via groups.permutation.PGU().

EXAMPLES:

sage: PGU(2,3)
The projective general unitary group of degree 2 over Finite Field of size 3

sage: G = PGU(2, 8, name='alpha'); G
The projective general unitary group of degree 2 over Finite Field in alpha of size 2^3
sage: G.base_ring()
Finite Field in alpha of size 2^3


TESTS:

sage: groups.permutation.PGU(2, 3)
The projective general unitary group of degree 2 over Finite Field of size 3

class sage.groups.perm_gps.permgroup_named.PSL(n, q, name='a')

The projective special linear groups over GF(q).

INPUT:

• n – positive integer; the degree
• q – either a prime power (the size of the ground field) or a finite field
• name – (default: ‘a’) variable name of indeterminate of finite field GF(q)

OUTPUT:

the group PSL(n,q)

Note

This group is also available via groups.permutation.PSL().

EXAMPLES:

sage: G = PSL(2,3); G
Permutation Group with generators [(2,3,4), (1,2)(3,4)]
sage: G.order()
12
sage: G.base_ring()
Finite Field of size 3
sage: print G
The projective special linear group of degree 2 over Finite Field of size 3


We create two groups over nontrivial finite fields:

sage: G = PSL(2, 4, 'b'); G
Permutation Group with generators [(3,4,5), (1,2,3)]
sage: G.base_ring()
Finite Field in b of size 2^2
sage: G = PSL(2, 8); G
Permutation Group with generators [(3,8,6,4,9,7,5), (1,2,3)(4,7,5)(6,9,8)]
sage: G.base_ring()
Finite Field in a of size 2^3

sage: G.category()
Category of finite permutation groups
sage: TestSuite(G).run() # long time


TESTS:

sage: groups.permutation.PSL(2, 3)
Permutation Group with generators [(2,3,4), (1,2)(3,4)]


Check that trac ticket #7424 is handled:

sage: PSL(2, GF(7,'x'))
Permutation Group with generators [(3,7,5)(4,8,6), (1,2,6)(3,4,8)]
sage: PSL(2, GF(3))
Permutation Group with generators [(2,3,4), (1,2)(3,4)]
sage: PSL(2, QQ)
Traceback (most recent call last):
...
ValueError: q must be a prime power or a finite field

ramification_module_decomposition_hurwitz_curve()

Helps compute the decomposition of the ramification module for the Hurwitz curves X (over CC say) with automorphism group G = PSL(2,q), q a “Hurwitz prime” (ie, p is $$\pm 1 \pmod 7$$). Using this computation and Borne’s formula helps determine the G-module structure of the RR spaces of equivariant divisors can be determined explicitly.

The output is a list of integer multiplicities: [m1,...,mn], where n is the number of conj classes of G=PSL(2,p) and mi is the multiplicity of pi_i in the ramification module of a Hurwitz curve with automorphism group G. Here IrrRepns(G) = [pi_1,...,pi_n] (in the order listed in the output of self.character_table()).

REFERENCE: David Joyner, Amy Ksir, Roger Vogeler,
“Group representations on Riemann-Roch spaces of some Hurwitz curves,” preprint, 2006.

EXAMPLES:

sage: G = PSL(2,13)
sage: G.ramification_module_decomposition_hurwitz_curve() # random, optional - database_gap
[0, 7, 7, 12, 12, 12, 13, 15, 14]


This means, for example, that the trivial representation does not occur in the ramification module of a Hurwitz curve with automorphism group PSL(2,13), since the trivial representation is listed first and that entry has multiplicity 0. The “randomness” is due to the fact that GAP randomly orders the conjugacy classes of the same order in the list of all conjugacy classes. Similarly, there is some randomness to the ordering of the characters.

If you try to use this function on a group PSL(2,q) where q is not a (smallish) “Hurwitz prime”, an error message will be printed.

ramification_module_decomposition_modular_curve()

Helps compute the decomposition of the ramification module for the modular curve X(p) (over CC say) with automorphism group G = PSL(2,q), q a prime > 5. Using this computation and Borne’s formula helps determine the G-module structure of the RR spaces of equivariant divisors can be determined explicitly.

The output is a list of integer multiplicities: [m1,...,mn], where n is the number of conj classes of G=PSL(2,p) and mi is the multiplicity of pi_i in the ramification module of a modular curve with automorphism group G. Here IrrRepns(G) = [pi_1,...,pi_n] (in the order listed in the output of self.character_table()).

REFERENCE: D. Joyner and A. Ksir, ‘Modular representations
on some Riemann-Roch spaces of modular curves $X(N)$’, Computational Aspects of Algebraic Curves, (Editor: T. Shaska) Lecture Notes in Computing, WorldScientific, 2005.)

EXAMPLES:

sage: G = PSL(2,7)
sage: G.ramification_module_decomposition_modular_curve() # random, optional - database_gap
[0, 4, 3, 6, 7, 8]


This means, for example, that the trivial representation does not occur in the ramification module of X(7), since the trivial representation is listed first and that entry has multiplicity 0. The “randomness” is due to the fact that GAP randomly orders the conjugacy classes of the same order in the list of all conjugacy classes. Similarly, there is some randomness to the ordering of the characters.

sage.groups.perm_gps.permgroup_named.PSP

alias of PSp

class sage.groups.perm_gps.permgroup_named.PSU(n, q, name='a')

The projective special unitary groups over GF(q).

INPUT:
n – positive integer; the degree q – prime power; the size of the ground field name – (default: ‘a’) variable name of indeterminate of finite field GF(q)
OUTPUT:
PSU(n,q)

Note

This group is also available via groups.permutation.PSU().

EXAMPLES:

sage: PSU(2,3)
The projective special unitary group of degree 2 over Finite Field of size 3

sage: G = PSU(2, 8, name='alpha'); G
The projective special unitary group of degree 2 over Finite Field in alpha of size 2^3
sage: G.base_ring()
Finite Field in alpha of size 2^3


TESTS:

sage: groups.permutation.PSU(2, 3)
The projective special unitary group of degree 2 over Finite Field of size 3

class sage.groups.perm_gps.permgroup_named.PSp(n, q, name='a')

The projective symplectic linear groups over GF(q).

INPUT:
n – positive integer; the degree q – prime power; the size of the ground field name – (default: ‘a’) variable name of indeterminate of finite field GF(q)
OUTPUT:
PSp(n,q)

Note

This group is also available via groups.permutation.PSp().

EXAMPLES:

sage: G = PSp(2,3); G
Permutation Group with generators [(2,3,4), (1,2)(3,4)]
sage: G.order()
12
sage: G = PSp(4,3); G
Permutation Group with generators [(3,4)(6,7)(9,10)(12,13)(17,20)(18,21)(19,22)(23,32)(24,33)(25,34)(26,38)(27,39)(28,40)(29,35)(30,36)(31,37), (1,5,14,17,27,22,19,36,3)(2,6,32)(4,7,23,20,37,13,16,26,40)(8,24,29,30,39,10,33,11,34)(9,15,35)(12,25,38)(21,28,31)]
sage: G.order()
25920
sage: print G
The projective symplectic linear group of degree 4 over Finite Field of size 3
sage: G.base_ring()
Finite Field of size 3

sage: G = PSp(2, 8, name='alpha'); G
Permutation Group with generators [(3,8,6,4,9,7,5), (1,2,3)(4,7,5)(6,9,8)]
sage: G.base_ring()
Finite Field in alpha of size 2^3


TESTS:

sage: groups.permutation.PSp(2, 3)
Permutation Group with generators [(2,3,4), (1,2)(3,4)]

class sage.groups.perm_gps.permgroup_named.PermutationGroup_plg(gens=None, gap_group=None, canonicalize=True, domain=None, category=None)

INPUT:

• gens - list of generators (default: None)
• gap_group - a gap permutation group (default: None)
• canonicalize - bool (default: True); if True, sort generators and remove duplicates

OUTPUT:

• A permutation group.

EXAMPLES:

We explicitly construct the alternating group on four elements:

sage: A4 = PermutationGroup([[(1,2,3)],[(2,3,4)]]); A4
Permutation Group with generators [(2,3,4), (1,2,3)]
sage: A4.__init__([[(1,2,3)],[(2,3,4)]]); A4
Permutation Group with generators [(2,3,4), (1,2,3)]
sage: A4.center()
Subgroup of (Permutation Group with generators [(2,3,4), (1,2,3)]) generated by [()]
sage: A4.category()
Category of finite permutation groups
sage: TestSuite(A4).run()


TESTS:

sage: TestSuite(PermutationGroup([[]])).run()
sage: TestSuite(PermutationGroup([])).run()
sage: TestSuite(PermutationGroup([(0,1)])).run()

base_ring()

EXAMPLES:

sage: G = PGL(2,3)
sage: G.base_ring()
Finite Field of size 3

sage: G = PSL(2,3)
sage: G.base_ring()
Finite Field of size 3

matrix_degree()

EXAMPLES:

sage: G = PSL(2,3)
sage: G.matrix_degree()
2

class sage.groups.perm_gps.permgroup_named.PermutationGroup_pug(gens=None, gap_group=None, canonicalize=True, domain=None, category=None)

INPUT:

• gens - list of generators (default: None)
• gap_group - a gap permutation group (default: None)
• canonicalize - bool (default: True); if True, sort generators and remove duplicates

OUTPUT:

• A permutation group.

EXAMPLES:

We explicitly construct the alternating group on four elements:

sage: A4 = PermutationGroup([[(1,2,3)],[(2,3,4)]]); A4
Permutation Group with generators [(2,3,4), (1,2,3)]
sage: A4.__init__([[(1,2,3)],[(2,3,4)]]); A4
Permutation Group with generators [(2,3,4), (1,2,3)]
sage: A4.center()
Subgroup of (Permutation Group with generators [(2,3,4), (1,2,3)]) generated by [()]
sage: A4.category()
Category of finite permutation groups
sage: TestSuite(A4).run()


TESTS:

sage: TestSuite(PermutationGroup([[]])).run()
sage: TestSuite(PermutationGroup([])).run()
sage: TestSuite(PermutationGroup([(0,1)])).run()

field_of_definition()

EXAMPLES:

sage: PSU(2,3).field_of_definition()
Finite Field in a of size 3^2

class sage.groups.perm_gps.permgroup_named.PermutationGroup_symalt(gens=None, gap_group=None, canonicalize=True, domain=None, category=None)

This is a class used to factor out some of the commonality in the SymmetricGroup and AlternatingGroup classes.

class sage.groups.perm_gps.permgroup_named.PermutationGroup_unique(gens=None, gap_group=None, canonicalize=True, domain=None, category=None)

Todo

Fix the broken hash.

sage: G = SymmetricGroup(6)
sage: G3 = G.subgroup([G((1,2,3,4,5,6)),G((1,2))])
sage: hash(G) == hash(G3)  # todo: Should be True!
False

class sage.groups.perm_gps.permgroup_named.PrimitiveGroup(d, n)

The primitive group from the GAP tables of primitive groups.

INPUT:

• d – non-negative integer. the degree of the group.
• n – positive integer. the index of the group in the GAP database, starting at 1

OUTPUT:

The n-th primitive group of degree d.

EXAMPLES:

sage: PrimitiveGroup(0,1)
Trivial group
sage: PrimitiveGroup(1,1)
Trivial group
sage: G = PrimitiveGroup(5, 2); G           # optional - database_gap
D(2*5)
sage: G.gens()                              # optional - database_gap
[(2,4)(3,5), (1,2,3,5,4)]
sage: G.category()                          # optional - database_gap
Category of finite permutation groups


Warning

this follows GAP’s naming convention of indexing the primitive groups starting from 1:

sage: PrimitiveGroup(5,0)               # optional - database_gap
Traceback (most recent call last):
...
ValueError: Index n must be in {1,..,5}


Only primitive groups of “small” degree are available in GAP’s database:

sage: PrimitiveGroup(2500,1)          # optional - database_gap
Traceback (most recent call last):
...
NotImplementedError: Only the primitive groups of degree less
than 2500 are available in GAP's database

group_primitive_id()

Return the index of this group in the GAP database of primitive groups.

Requires “optional” database_gap package.

OUTPUT:

A positive integer, following GAP’s conventions.

EXAMPLES:

sage: G = PrimitiveGroup(5,2); G.group_primitive_id()  # optional - database_gap
2

sage.groups.perm_gps.permgroup_named.PrimitiveGroups(d=None)

Return the set of all primitive groups of a given degree d

INPUT:

• d – an integer (optional)

OUTPUT:

The set of all primitive groups of a given degree d up to isomorphisms using GAP. If d is not specified, it returns the set of all primitive groups up to isomorphisms stored in GAP.

Attention

PrimitiveGroups requires the optional GAP database package. Please install it with install_package(database_gap').

EXAMPLES:

sage: PrimitiveGroups(3)
Primitive Groups of degree 3
sage: PrimitiveGroups(7)
Primitive Groups of degree 7
sage: PrimitiveGroups(8)
Primitive Groups of degree 8
sage: PrimitiveGroups()
Primitive Groups


The database currently only contains primitive groups up to degree 2499:

sage: PrimitiveGroups(2500).cardinality() # optional - database_gap
Traceback (most recent call last):
...
NotImplementedError: Only the primitive groups of degree less
than 2500 are available in GAP's database


TODO:

This enumeration helper could be extended based on PrimitiveGroupsIterator in GAP. This method allows to enumerate groups with specified properties such as transitivity, solvability, ..., without creating all groups.

class sage.groups.perm_gps.permgroup_named.PrimitiveGroupsAll

The infinite set of all primitive groups up to isomorphisms.

EXAMPLES:

sage: L = PrimitiveGroups(); L
Primitive Groups
sage: L.category()
Category of infinite enumerated sets
sage: L.cardinality()
+Infinity

sage: p = L.__iter__()            # optional - database_gap
sage: (next(p), next(p), next(p), next(p), # optional - database_gap
...    next(p), next(p), next(p), next(p))
(Trivial group, Trivial group, S(2), A(3), S(3), A(4), S(4), C(5))


TESTS:

sage: TestSuite(PrimitiveGroups()).run() # optional - database_gap # long time

class sage.groups.perm_gps.permgroup_named.PrimitiveGroupsOfDegree(n)

The set of all primitive groups of a given degree up to isomorphisms.

EXAMPLES:

sage: S = PrimitiveGroups(5); S       # optional - database_gap
Primitive Groups of degree 5
sage: S.list()                          # optional - database_gap
[C(5), D(2*5), AGL(1, 5), A(5), S(5)]
sage: S.an_element() # optional - database_gap
C(5)


We write the cardinality of all primitive groups of degree 5:

sage: for G in PrimitiveGroups(5):    # optional - database_gap
...       print G.cardinality()
5
10
20
60
120


TESTS:

sage: TestSuite(PrimitiveGroups(3)).run() # optional - database_gap

cardinality()

Return the cardinality of self.

OUTPUT:

An integer. The number of primitive groups of a given degree up to isomorphism.

EXAMPLES:

sage: PrimitiveGroups(0).cardinality()                      # optional - database_gap
1
sage: PrimitiveGroups(2).cardinality()                      # optional - database_gap
1
sage: PrimitiveGroups(7).cardinality()                      # optional - database_gap
7
sage: PrimitiveGroups(12).cardinality()                     # optional - database_gap
6
sage: [PrimitiveGroups(i).cardinality() for i in range(11)] # optional - database_gap
[1, 1, 1, 2, 2, 5, 4, 7, 7, 11, 9]


The database_gap contains all primitive groups up to degree 2499:

sage: PrimitiveGroups(2500).cardinality()                     # optional - database_gap
Traceback (most recent call last):
...
NotImplementedError: Only the primitive groups of degree less than
2500 are available in GAP's database


TESTS:

sage: type(PrimitiveGroups(12).cardinality())               # optional - database_gap
<type 'sage.rings.integer.Integer'>
sage: type(PrimitiveGroups(0).cardinality())
<type 'sage.rings.integer.Integer'>

class sage.groups.perm_gps.permgroup_named.QuaternionGroup

The quaternion group of order 8.

OUTPUT:
The quaternion group of order 8, as a permutation group. See the DiCyclicGroup class for a generalization of this construction.

Note

This group is also available via groups.permutation.Quaternion().

EXAMPLES:

The quaternion group is one of two non-abelian groups of order 8, the other being the dihedral group $$D_4$$. One way to describe this group is with three generators, $$I, J, K$$, so the whole group is then given as the set $$\{\pm 1, \pm I, \pm J, \pm K\}$$ with relations such as $$I^2=J^2=K^2=-1$$, $$IJ=K$$ and $$JI=-K$$.

The examples below illustrate how to use this group in a similar manner, by testing some of these relations. The representation used here is the left-regular representation.

sage: Q = QuaternionGroup()
sage: I = Q.gen(0)
sage: J = Q.gen(1)
sage: K = I*J
sage: [I,J,K]
[(1,2,3,4)(5,6,7,8), (1,5,3,7)(2,8,4,6), (1,8,3,6)(2,7,4,5)]
sage: neg_one = I^2; neg_one
(1,3)(2,4)(5,7)(6,8)
sage: J^2 == neg_one and K^2 == neg_one
True
sage: J*I == neg_one*K
True
sage: Q.center().order() == 2
True
sage: neg_one in Q.center()
True


TESTS:

sage: groups.permutation.Quaternion()
Quaternion group of order 8 as a permutation group

AUTHOR:
– Rob Beezer (2009-10-09)
class sage.groups.perm_gps.permgroup_named.SemidihedralGroup(m)

The semidihedral group of order $$2^m$$.

INPUT:

• m - a positive integer; the power of 2 that is the group’s order

OUTPUT:

The semidihedral group of order $$2^m$$. These groups can be thought of as a semidirect product of $$C_{2^{m-1}}$$ with $$C_2$$, where the nontrivial element of $$C_2$$ is sent to the element of the automorphism group of $$C_{2^{m-1}}$$ that sends elements to their $$-1+2^{m-2}$$ th power. Thus, the group has the presentation:

$\langle x, y\mid x^{2^{m-1}}, y^{2}, y^{-1}xy=x^{-1+2^{m-2}} \rangle$

This family is notable because it is made up of non-abelian 2-groups that all contain cyclic subgroups of index 2. It is one of only four such families.

EXAMPLES:

In [GORENSTEIN1980] it is shown that the semidihedral groups have center of order 2. It is also shown that they have a Frattini subgroup equal to their commutator, which is a cyclic subgroup of order $$2^{m-2}$$.

sage: G = SemidihedralGroup(12)
sage: G.order() == 2^12
True
sage: G.commutator() == G.frattini_subgroup()
True
sage: G.commutator().order() == 2^10
True
sage: G.commutator().is_cyclic()
True
sage: G.center().order()
2

sage: G = SemidihedralGroup(4)
sage: len([H for H in G.subgroups() if H.is_cyclic() and H.order() == 8])
1
sage: G.gens()
[(2,4)(3,7)(6,8), (1,2,3,4,5,6,7,8)]
sage: x = G.gens()[1]; y = G.gens()[0]
sage: x.order() == 2^3; y.order() == 2
True
True
sage: y*x*y == x^(-1+2^2)
True


TESTS:

sage: G = SemidihedralGroup(4.4)
Traceback (most recent call last):
...
TypeError: m must be an integer, not 4.40000000000000

sage: G = SemidihedralGroup(-5)
Traceback (most recent call last):
...
ValueError: the exponent must be greater than 3, not -5


REFERENCES:

 [GORENSTEIN1980] Daniel Gorenstein, Finite Groups (New York: Chelsea Publishing, 1980)

AUTHOR:

• Kevin Halasz (2012-8-7)
class sage.groups.perm_gps.permgroup_named.SplitMetacyclicGroup(p, m)

The split metacyclic group of order $$p^m$$.

INPUT:

• p - a prime number that is the prime underlying this p-group
• m - a positive integer such that the order of this group is the $$p^m$$. Be aware that, for even $$p$$, $$m$$ must be greater than 3, while for odd $$p$$, $$m$$ must be greater than 2.

OUTPUT:

The split metacyclic group of order $$p^m$$. This family of groups has presentation

$\langle x, y\mid x^{p^{m-1}}, y^{p}, y^{-1}xy=x^{1+p^{m-2}} \rangle$

This family is notable because, for odd $$p$$, these are the only $$p$$-groups with a cyclic subgroup of index $$p$$, a result proven in [GORENSTEIN]. It is also shown in [GORENSTEIN] that this is one of four families containing nonabelian 2-groups with a cyclic subgroup of index 2 (with the others being the dicyclic groups, the dihedral groups, and the semidihedral groups).

EXAMPLES:

Using the last relation in the group’s presentation, one can see that the elements of the form $$y^{i}x$$, $$0 \leq i \leq p-1$$ all have order $$p^{m-1}$$, as it can be shown that their $$p$$ th powers are all $$x^{p^{m-2}+p}$$, an element with order $$p^{m-2}$$. Manipulation of the same relation shows that none of these elements are powers of any other. Thus, there are $$p$$ cyclic maximal subgroups in each split metacyclic group. It is also proven in [GORENSTEIN] that this family has commutator subgroup of order $$p$$, and the Frattini subgroup is equal to the center, with this group being cyclic of order $$p^{m-2}$$. These characteristics are necessary to identify these groups in the case that $$p=2$$, although the possession of a cyclic maximal subgroup in a non-abelian $$p$$-group is enough for odd $$p$$ given the group’s order.

sage: G = SplitMetacyclicGroup(2,8)
sage: G.order() == 2**8
True
sage: G.is_abelian()
False
sage: len([H for H in G.subgroups() if H.order() == 2^7 and H.is_cyclic()])
2
sage: G.commutator().order()
2
sage: G.frattini_subgroup() == G.center()
True
sage: G.center().order() == 2^6
True
sage: G.center().is_cyclic()
True

sage: G = SplitMetacyclicGroup(3,3)
sage: len([H for H in G.subgroups() if H.order() == 3^2 and H.is_cyclic()])
3
sage: G.commutator().order()
3
sage: G.frattini_subgroup() == G.center()
True
sage: G.center().order()
3


TESTS:

sage: G = SplitMetacyclicGroup(3,2.5)
Traceback (most recent call last):
...
TypeError: both p and m must be integers

sage: G = SplitMetacyclicGroup(4,3)
Traceback (most recent call last):
...
ValueError: p must be prime, 4 is not prime

sage: G = SplitMetacyclicGroup(2,2)
Traceback (most recent call last):
...
ValueError: if prime is 2, the exponent must be greater than 3, not 2

sage: G = SplitMetacyclicGroup(11,2)
Traceback (most recent call last):
...
ValueError: if prime is odd, the exponent must be greater than 2, not 2


REFERENCES:

 [GORENSTEIN] (1, 2, 3) Daniel Gorenstein, Finite Groups (New York: Chelsea Publishing, 1980)

AUTHOR:

• Kevin Halasz (2012-8-7)
class sage.groups.perm_gps.permgroup_named.SuzukiGroup(q, name='a')

The Suzuki group over GF(q), $$^2 B_2(2^{2k+1}) = Sz(2^{2k+1})$$.

A wrapper for the GAP function SuzukiGroup.

INPUT:
q – 2^n, an odd power of 2; the size of the ground
field. (Strictly speaking, n should be greater than 1, or else this group os not simple.)
name – (default: ‘a’) variable name of indeterminate of
finite field GF(q)

OUTPUT:

• A Suzuki group.

Note

This group is also available via groups.permutation.Suzuki().

EXAMPLES:

sage: SuzukiGroup(8)
Permutation Group with generators [(1,2)(3,10)(4,42)(5,18)(6,50)(7,26)(8,58)(9,34)(12,28)(13,45)(14,44)(15,23)(16,31)(17,21)(19,39)(20,38)(22,25)(24,61)(27,60)(29,65)(30,55)(32,33)(35,52)(36,49)(37,59)(40,54)(41,62)(43,53)(46,48)(47,56)(51,63)(57,64),
(1,28,10,44)(3,50,11,42)(4,43,53,64)(5,9,39,52)(6,36,63,13)(7,51,60,57)(8,33,37,16)(12,24,55,29)(14,30,48,47)(15,19,61,54)(17,59,22,62)(18,23,34,31)(20,38,49,25)(21,26,45,58)(27,32,41,65)(35,46,40,56)]
sage: print SuzukiGroup(8)
The Suzuki group over Finite Field in a of size 2^3

sage: G = SuzukiGroup(32, name='alpha')
sage: G.order()
32537600
sage: G.order().factor()
2^10 * 5^2 * 31 * 41
sage: G.base_ring()
Finite Field in alpha of size 2^5


TESTS:

sage: groups.permutation.Suzuki(8)
Permutation Group with generators [(1,2)(3,10)(4,42)(5,18)(6,50)(7,26)(8,58)(9,34)(12,28)(13,45)(14,44)(15,23)(16,31)(17,21)(19,39)(20,38)(22,25)(24,61)(27,60)(29,65)(30,55)(32,33)(35,52)(36,49)(37,59)(40,54)(41,62)(43,53)(46,48)(47,56)(51,63)(57,64),
(1,28,10,44)(3,50,11,42)(4,43,53,64)(5,9,39,52)(6,36,63,13)(7,51,60,57)(8,33,37,16)(12,24,55,29)(14,30,48,47)(15,19,61,54)(17,59,22,62)(18,23,34,31)(20,38,49,25)(21,26,45,58)(27,32,41,65)(35,46,40,56)]


REFERENCES:

base_ring()

EXAMPLES:

sage: G = SuzukiGroup(32, name='alpha')
sage: G.base_ring()
Finite Field in alpha of size 2^5

class sage.groups.perm_gps.permgroup_named.SymmetricGroup(domain=None)

The full symmetric group of order $$n!$$, as a permutation group.

If $$n$$ is a list or tuple of positive integers then it returns the symmetric group of the associated set.

INPUT:

• n – a positive integer, or list or tuple thereof

Note

This group is also available via groups.permutation.Symmetric().

EXAMPLES:

sage: G = SymmetricGroup(8)
sage: G.order()
40320
sage: G
Symmetric group of order 8! as a permutation group
sage: G.degree()
8
sage: S8 = SymmetricGroup(8)
sage: G = SymmetricGroup([1,2,4,5])
sage: G
Symmetric group of order 4! as a permutation group
sage: G.domain()
{1, 2, 4, 5}
sage: G = SymmetricGroup(4)
sage: G
Symmetric group of order 4! as a permutation group
sage: G.domain()
{1, 2, 3, 4}
sage: G.category()
Join of Category of finite permutation groups
and Category of finite weyl groups


TESTS:

sage: groups.permutation.Symmetric(4)
Symmetric group of order 4! as a permutation group

algebra(base_ring)

Return the symmetric group algebra associated to self.

EXAMPLES:

sage: S4 = SymmetricGroup(4)
sage: S4.algebra(QQ)
Symmetric group algebra of order 4 over Rational Field

cartan_type()

Return the Cartan type of self

The symmetric group $$S_n$$ is a Coxeter group of type $$A_{n-1}$$.

EXAMPLES:

sage: A = SymmetricGroup([2,3,7]); A.cartan_type()
['A', 2]

conjugacy_class(g)

Return the conjugacy class of g inside the symmetric group self.

INPUT:

• g – a partition or an element of the symmetric group self

OUTPUT:

A conjugacy class of a symmetric group.

EXAMPLES:

sage: G = SymmetricGroup(5)
sage: g = G((1,2,3,4))
sage: G.conjugacy_class(g)
Conjugacy class of cycle type [4, 1] in
Symmetric group of order 5! as a permutation group

conjugacy_classes()

Return a list of the conjugacy classes of self.

EXAMPLES:

sage: G = SymmetricGroup(5)
sage: G.conjugacy_classes()
[Conjugacy class of cycle type [1, 1, 1, 1, 1] in
Symmetric group of order 5! as a permutation group,
Conjugacy class of cycle type [2, 1, 1, 1] in
Symmetric group of order 5! as a permutation group,
Conjugacy class of cycle type [2, 2, 1] in
Symmetric group of order 5! as a permutation group,
Conjugacy class of cycle type [3, 1, 1] in
Symmetric group of order 5! as a permutation group,
Conjugacy class of cycle type [3, 2] in
Symmetric group of order 5! as a permutation group,
Conjugacy class of cycle type [4, 1] in
Symmetric group of order 5! as a permutation group,
Conjugacy class of cycle type [5] in
Symmetric group of order 5! as a permutation group]

conjugacy_classes_iterator()

Iterate over the conjugacy classes of self.

EXAMPLES:

sage: G = SymmetricGroup(5)
sage: list(G.conjugacy_classes_iterator()) == G.conjugacy_classes()
True

conjugacy_classes_representatives()

Return a complete list of representatives of conjugacy classes in a permutation group $$G$$.

Let $$S_n$$ be the symmetric group on $$n$$ letters. The conjugacy classes are indexed by partitions $$\lambda$$ of $$n$$. The ordering of the conjugacy classes is reverse lexicographic order of the partitions.

EXAMPLES:

sage: G = SymmetricGroup(5)
sage: G.conjugacy_classes_representatives()
[(), (1,2), (1,2)(3,4), (1,2,3), (1,2,3)(4,5),
(1,2,3,4), (1,2,3,4,5)]

sage: S = SymmetricGroup(['a','b','c'])
sage: S.conjugacy_classes_representatives()
[(), ('a','b'), ('a','b','c')]


TESTS:

Check some border cases:

sage: S = SymmetricGroup(0)
sage: S.conjugacy_classes_representatives()
[()]
sage: S = SymmetricGroup(1)
sage: S.conjugacy_classes_representatives()
[()]

index_set()

Return the index set for the descents of the symmetric group self.

EXAMPLES:

sage: S8 = SymmetricGroup(8)
sage: S8.index_set()
[1, 2, 3, 4, 5, 6, 7]

sage: S = SymmetricGroup([3,1,4,5])
sage: S.index_set()
[3, 1, 4]

major_index(parameter=None)

Return the major index generating polynomial of self, which is a gadget counting the elements of self by major index.

INPUT:

• parameter – an element of a ring; the result is more explicit with a formal variable (default: element q of Univariate Polynomial Ring in q over Integer Ring)
$P(q) = \sum_{g\in S_n} q^{ \operatorname{major\ index}(g) }$

EXAMPLES:

sage: S4 = SymmetricGroup(4)
sage: S4.major_index()
q^6 + 3*q^5 + 5*q^4 + 6*q^3 + 5*q^2 + 3*q + 1
sage: K.<t> = QQ[]
sage: S4.major_index(t)
t^6 + 3*t^5 + 5*t^4 + 6*t^3 + 5*t^2 + 3*t + 1

simple_reflection(i)

For $$i$$ in the index set of self, this returns the elementary transposition $$s_i = (i,i+1)$$.

EXAMPLES:

sage: A = SymmetricGroup(5)
sage: A.simple_reflection(3)
(3,4)

sage: A = SymmetricGroup([2,3,7])
sage: A.simple_reflections()
Finite family {2: (2,3), 3: (3,7)}

young_subgroup(comp)

Return the Young subgroup associated with the composition comp.

EXAMPLES:

sage: S = SymmetricGroup(8)
sage: c = Composition([2,2,2,2])
sage: S.young_subgroup(c)
Subgroup of (Symmetric group of order 8! as a permutation group)
generated by [(7,8), (5,6), (3,4), (1,2)]

sage: S = SymmetricGroup(['a','b','c'])
sage: S.young_subgroup([2,1])
Subgroup of (Symmetric group of order 3! as a permutation group)
generated by [('a','b')]

sage: Y = S.young_subgroup([2,2,2,2,2])
Traceback (most recent call last):
...
ValueError: The composition is not of expected size

class sage.groups.perm_gps.permgroup_named.TransitiveGroup(d, n)

The transitive group from the GAP tables of transitive groups.

INPUT:
d – non-negative integer; the degree n – positive integer; the index of the group in the GAP database, starting at 1
OUTPUT:
the n-th transitive group of degree d

Note

This group is also available via groups.permutation.Transitive().

EXAMPLES:

sage: TransitiveGroup(0,1)
Transitive group number 1 of degree 0
sage: TransitiveGroup(1,1)
Transitive group number 1 of degree 1
sage: G = TransitiveGroup(5, 2); G         # optional - database_gap
Transitive group number 2 of degree 5
sage: G.gens()                             # optional - database_gap
[(1,2,3,4,5), (1,4)(2,3)]

sage: G.category()                         # optional - database_gap
Category of finite permutation groups


Warning

this follows GAP’s naming convention of indexing the transitive groups starting from 1:

sage: TransitiveGroup(5,0)                 # optional - database_gap
Traceback (most recent call last):
...
ValueError: Index n must be in {1,..,5}


Warning

only transitive groups of “small” degree are available in GAP’s database:

sage: TransitiveGroup(31,1)                # optional - database_gap
Traceback (most recent call last):
...
NotImplementedError: Only the transitive groups of order less than 30 are available in GAP's database


TESTS:

sage: groups.permutation.Transitive(1, 1)
Transitive group number 1 of degree 1

sage: TestSuite(TransitiveGroup(0,1)).run()
sage: TestSuite(TransitiveGroup(1,1)).run()
sage: TestSuite(TransitiveGroup(5,2)).run()# optional - database_gap

sage: TransitiveGroup(1,5)                 # optional - database_gap
Traceback (most recent call last):
...
ValueError: Index n must be in {1,..,1}

sage.groups.perm_gps.permgroup_named.TransitiveGroups(d=None)

INPUT:

• d – an integer (optional)

Returns the set of all transitive groups of a given degree d up to isomorphisms. If d is not specified, it returns the set of all transitive groups up to isomorphisms.

Warning: TransitiveGroups requires the optional GAP database package. Please install it with sage -i database_gap.

EXAMPLES:

sage: TransitiveGroups(3)
Transitive Groups of degree 3
sage: TransitiveGroups(7)
Transitive Groups of degree 7
sage: TransitiveGroups(8)
Transitive Groups of degree 8

sage: TransitiveGroups()
Transitive Groups


Warning

in practice, the database currently only contains transitive groups up to degree 30:

sage: TransitiveGroups(31).cardinality() # optional - database_gap
Traceback (most recent call last):
...
NotImplementedError: Only the transitive groups of order less than 30 are available in GAP's database

class sage.groups.perm_gps.permgroup_named.TransitiveGroupsAll

The infinite set of all transitive groups up to isomorphisms.

EXAMPLES:

sage: L = TransitiveGroups(); L
Transitive Groups
sage: L.category()
Category of infinite enumerated sets
sage: L.cardinality()
+Infinity

sage: p = L.__iter__()            # optional - database_gap
sage: (next(p), next(p), next(p), next(p), next(p), next(p), next(p), next(p)) # optional - database_gap
(Transitive group number 1 of degree 0, Transitive group number 1 of degree 1, Transitive group number 1 of degree 2, Transitive group number 1 of degree 3, Transitive group number 2 of degree 3, Transitive group number 1 of degree 4, Transitive group number 2 of degree 4, Transitive group number 3 of degree 4)


TESTS:

sage: TestSuite(TransitiveGroups()).run() # optional - database_gap # long time

class sage.groups.perm_gps.permgroup_named.TransitiveGroupsOfDegree(n)

The set of all transitive groups of a given (small) degree up to isomorphisms.

EXAMPLES:

sage: S = TransitiveGroups(4); S       # optional - database_gap
Transitive Groups of degree 4
sage: list(S)                          # optional - database_gap
[Transitive group number 1 of degree 4, Transitive group number 2 of degree 4, Transitive group number 3 of degree 4, Transitive group number 4 of degree 4, Transitive group number 5 of degree 4]

sage: TransitiveGroups(5).an_element() # optional - database_gap
Transitive group number 1 of degree 5


We write the cardinality of all transitive groups of degree 5:

sage: for G in TransitiveGroups(5):    # optional - database_gap
...       print G.cardinality()
5
10
20
60
120


TESTS:

sage: TestSuite(TransitiveGroups(3)).run() # optional - database_gap

cardinality()

Returns the cardinality of self, that is the number of transitive groups of a given degree.

EXAMPLES:

sage: TransitiveGroups(0).cardinality()                      # optional - database_gap
1
sage: TransitiveGroups(2).cardinality()                      # optional - database_gap
1
sage: TransitiveGroups(7).cardinality()                      # optional - database_gap
7
sage: TransitiveGroups(12).cardinality()                     # optional - database_gap
301
sage: [TransitiveGroups(i).cardinality() for i in range(11)] # optional - database_gap
[1, 1, 1, 2, 5, 5, 16, 7, 50, 34, 45]


Warning

The database_gap contains all transitive groups up to degree 30:

sage: TransitiveGroups(31).cardinality()                     # optional - database_gap
Traceback (most recent call last):
...
NotImplementedError: Only the transitive groups of order less than 30 are available in GAP's database


TESTS:

sage: type(TransitiveGroups(12).cardinality())               # optional - database_gap
<type 'sage.rings.integer.Integer'>
sage: type(TransitiveGroups(0).cardinality())
<type 'sage.rings.integer.Integer'>
`

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