Common combinatorial tools

REFERENCES:

[NCSF](1, 2, 3, 4) Gelfand, Krob, Lascoux, Leclerc, Retakh, Thibon, Noncommutative Symmetric Functions, Adv. Math. 112 (1995), no. 2, 218-348.
[QSCHUR]Haglund, Luoto, Mason, van Willigenburg, Quasisymmetric Schur functions, J. Comb. Theory Ser. A 118 (2011), 463-490. http://www.sciencedirect.com/science/article/pii/S0097316509001745 , Arxiv 0810.2489v2.
[Tev2007]Lenny Tevlin, Noncommutative Analogs of Monomial Symmetric Functions, Cauchy Identity, and Hall Scalar Product, Arxiv 0712.2201v1.
sage.combinat.ncsf_qsym.combinatorics.coeff_dab(I, J)

Return the number of standard composition tableaux of shape \(I\) with descent composition \(J\).

INPUT:

  • I, J – compositions

OUTPUT:

  • An integer

EXAMPLES:

sage: from sage.combinat.ncsf_qsym.combinatorics import coeff_dab
sage: coeff_dab(Composition([2,1]),Composition([2,1]))
1
sage: coeff_dab(Composition([1,1,2]),Composition([1,2,1]))
0
sage.combinat.ncsf_qsym.combinatorics.coeff_ell(J, I)

Returns the coefficient \(\ell_{J,I}\) as defined in [NCSF].

INPUT:

  • J – a composition
  • I – a composition refining J

OUTPUT:

  • integer

EXAMPLES:

sage: from sage.combinat.ncsf_qsym.combinatorics import coeff_ell
sage: coeff_ell(Composition([1,1,1]), Composition([2,1]))
2
sage: coeff_ell(Composition([2,1]), Composition([3]))
2
sage.combinat.ncsf_qsym.combinatorics.coeff_lp(J, I)

Returns the coefficient \(lp_{J,I}\) as defined in [NCSF].

INPUT:

  • J – a composition
  • I – a composition refining J

OUTPUT:

  • integer

EXAMPLES:

sage: from sage.combinat.ncsf_qsym.combinatorics import coeff_lp
sage: coeff_lp(Composition([1,1,1]), Composition([2,1]))
1
sage: coeff_lp(Composition([2,1]), Composition([3]))
1
sage.combinat.ncsf_qsym.combinatorics.coeff_pi(J, I)

Returns the coefficient \(\pi_{J,I}\) as defined in [NCSF].

INPUT:

  • J – a composition
  • I – a composition refining J

OUTPUT:

  • integer

EXAMPLES:

sage: from sage.combinat.ncsf_qsym.combinatorics import coeff_pi
sage: coeff_pi(Composition([1,1,1]), Composition([2,1]))
2
sage: coeff_pi(Composition([2,1]), Composition([3]))
6
sage.combinat.ncsf_qsym.combinatorics.coeff_sp(J, I)

Returns the coefficient \(sp_{J,I}\) as defined in [NCSF].

INPUT:

  • J – a composition
  • I – a composition refining J

OUTPUT:

  • integer

EXAMPLES:

sage: from sage.combinat.ncsf_qsym.combinatorics import coeff_sp
sage: coeff_sp(Composition([1,1,1]), Composition([2,1]))
2
sage: coeff_sp(Composition([2,1]), Composition([3]))
4
sage.combinat.ncsf_qsym.combinatorics.compositions_order(n)

Return the compositions of \(n\) ordered as defined in [QSCHUR].

Let \(S(\gamma)\) return the composition \(\gamma\) after sorting. For compositions \(\alpha\) and \(\beta\), we order \(\alpha \rhd \beta\) if

  1. \(S(\alpha) > S(\beta)\) lexicographically, or
  2. \(S(\alpha) = S(\beta)\) and \(\alpha > \beta\) lexicographically.

INPUT:

  • n – a positive integer

OUTPUT:

  • A list of the compositions of n sorted into decreasing order by \(\rhd\)

EXAMPLES:

sage: from sage.combinat.ncsf_qsym.combinatorics import compositions_order
sage: compositions_order(3)
[[3], [2, 1], [1, 2], [1, 1, 1]]
sage: compositions_order(4)
[[4], [3, 1], [1, 3], [2, 2], [2, 1, 1], [1, 2, 1], [1, 1, 2], [1, 1, 1, 1]]
sage.combinat.ncsf_qsym.combinatorics.m_to_s_stat(R, I, K)

Return the coefficient of the complete non-commutative symmetric function \(S^K\) in the expansion of the monomial non-commutative symmetric function \(M^I\) with respect to the complete basis over the ring \(R\). This is the coefficient in formula (36) of Tevlin’s paper [Tev2007].

INPUT:

  • R – A ring, supposed to be a \(\QQ\)-algebra
  • I, K – compositions

OUTPUT:

  • The coefficient of \(S^K\) in the expansion of \(M^I\) in the complete basis of the non-commutative symmetric functions over R.

EXAMPLES:

sage: from sage.combinat.ncsf_qsym.combinatorics import m_to_s_stat
sage: m_to_s_stat(QQ, Composition([2,1]), Composition([1,1,1]))
-1
sage: m_to_s_stat(QQ, Composition([3]), Composition([1,2]))
-2
sage: m_to_s_stat(QQ, Composition([2,1,2]), Composition([2,1,2]))
8/3
sage.combinat.ncsf_qsym.combinatorics.number_of_fCT(content_comp, shape_comp)

Return the number of Immaculate tableaux of shape shape_comp and content content_comp.

See [BBSSZ2012], Definition 3.9, for the notion of an immaculate tableau.

INPUT:

  • content_comp, shape_comp – compositions

OUTPUT:

  • An integer

EXAMPLES:

sage: from sage.combinat.ncsf_qsym.combinatorics import number_of_fCT
sage: number_of_fCT(Composition([3,1]), Composition([1,3]))
0
sage: number_of_fCT(Composition([1,2,1]), Composition([1,3]))
1
sage: number_of_fCT(Composition([1,1,3,1]), Composition([2,1,3]))
2

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