Ordered Multiset Partitions into Sets and the Minimaj Crystal¶

This module provides element and parent classes for ordered multiset partitions. It also implements the minimaj crystal of Benkart et al. [BCHOPSY2017]. (See MinimajCrystal.)

AUTHORS:

• Aaron Lauve (2018): initial implementation. First draft of minimaj crystal code provided by Anne Schilling.

REFERENCES:

EXAMPLES:

An ordered multiset partition into sets of the multiset $$\{\{1, 3, 3, 5\}\}$$:

sage: OrderedMultisetPartitionIntoSets([[5, 3], [1, 3]])
[{3,5}, {1,3}]


Ordered multiset partitions into sets of the multiset $$\{\{1, 3, 3\}\}$$:

sage: OrderedMultisetPartitionsIntoSets([1,1,3]).list()
[[{1}, {1}, {3}], [{1}, {1,3}], [{1}, {3}, {1}], [{1,3}, {1}], [{3}, {1}, {1}]]


Ordered multiset partitions into sets of the integer 4:

sage: OrderedMultisetPartitionsIntoSets(4).list()
[[{4}], [{1,3}], [{3}, {1}], [{1,2}, {1}], [{2}, {2}], [{2}, {1}, {1}],
[{1}, {3}], [{1}, {1,2}], [{1}, {2}, {1}], [{1}, {1}, {2}], [{1}, {1}, {1}, {1}]]


Ordered multiset partitions into sets on the alphabet $$\{1, 4\}$$ of order 3:

sage: OrderedMultisetPartitionsIntoSets([1,4], 3).list()
[[{1,4}, {1}], [{1,4}, {4}], [{1}, {1,4}], [{4}, {1,4}], [{1}, {1}, {1}],
[{1}, {1}, {4}], [{1}, {4}, {1}], [{1}, {4}, {4}], [{4}, {1}, {1}],
[{4}, {1}, {4}], [{4}, {4}, {1}], [{4}, {4}, {4}]]


Crystal of ordered multiset partitions into sets on the alphabet $$\{1,2,3\}$$ with 4 letters divided into 2 blocks:

sage: crystals.Minimaj(3, 4, 2).list()
[((2, 3, 1), (1,)), ((2, 3), (1, 2)), ((2, 3), (1, 3)), ((2, 1), (1, 2)),
((3, 1), (1, 2)), ((3, 1, 2), (2,)), ((3, 1), (1, 3)), ((3, 1), (2, 3)),
((3, 2), (2, 3)), ((2, 1), (1, 3)), ((2,), (1, 2, 3)), ((3,), (1, 2, 3)),
((1,), (1, 2, 3)), ((1, 2), (2, 3)), ((1, 2, 3), (3,))]

class sage.combinat.multiset_partition_into_sets_ordered.MinimajCrystal(n, ell, k)

Crystal of ordered multiset partitions into sets with $$ell$$ letters from alphabet $$\{1, 2, \ldots, n\}$$ divided into $$k$$ blocks.

Elements are represented in the minimaj ordering of blocks as in Benkart et al. [BCHOPSY2017].

Note

Elements are not stored internally as ordered multiset partitions into sets, but as certain (pairs of) words stemming from the minimaj bijection $$\phi$$ of [BCHOPSY2017]. See sage.combinat.multiset_partition_into_sets_ordered.MinimajCrystal.Element for further details.

AUTHORS:

• Anne Schilling (2018): initial draft

• Aaron Lauve (2018): changed to use Letters crystal for elements

EXAMPLES:

sage: list(crystals.Minimaj(2,3,2))
[((2, 1), (1,)), ((2,), (1, 2)), ((1,), (1, 2)), ((1, 2), (2,))]

sage: b = crystals.Minimaj(3, 5, 2).an_element(); b
((2, 3, 1), (1, 2))
sage: b.f(2)
((2, 3, 1), (1, 3))
sage: b.e(2)

class Element

An element of a Minimaj crystal.

Note

Minimaj elements $$b$$ are stored internally as pairs (w, breaks), where:

• w is a word of length self.parent().ell over the letters $$1$$ up to self.parent().n;

• breaks is a list of de-concatenation points to turn w into a list of row words of (skew-)tableaux that represent $$b$$ under the minimaj bijection $$\phi$$ of [BCHOPSY2017].

The pair (w, breaks) may be recovered via b.value.

e(i)

Return $$e_i$$ on self.

EXAMPLES:

sage: B = crystals.Minimaj(4,3,2)
sage: b = B([[2,3], [3]]); b
((2, 3), (3,))
sage: [b.e(i) for i in range(1,4)]
[((1, 3), (3,)), ((2,), (2, 3)), None]

f(i)

Return $$f_i$$ on self.

EXAMPLES:

sage: B = crystals.Minimaj(4,3,2)
sage: b = B([[2,3], [3]]); b
((2, 3), (3,))
sage: [b.f(i) for i in range(1,4)]
[None, None, ((2, 3), (4,))]

to_tableaux_words()

Return the image of the ordered multiset partition into sets self under the minimaj bijection $$\phi$$ of [BCHOPSY2017].

EXAMPLES:

sage: B = crystals.Minimaj(4,5,3)
sage: b = B.an_element(); b
((2, 3, 1), (1,), (1,))
sage: b.to_tableaux_words()
[[1], [3], [2, 1, 1]]

sage: b = B([[1,3,4], [3], [3]]); b
((4, 1, 3), (3,), (3,))
sage: b.to_tableaux_words()
[[3, 1], [], [4, 3, 3]]

from_tableau(t)

Return the bijection $$\phi^{-1}$$ of [BCHOPSY2017] applied to t.

INPUT:

• t – a sequence of column tableaux and a ribbon tableau

EXAMPLES:

sage: B = crystals.Minimaj(3,6,3)
sage: b = B.an_element(); b
((3, 1, 2), (2, 1), (1,))
sage: t = b.to_tableaux_words(); t
[[1], [2, 1], [], [3, 2, 1]]
sage: B.from_tableau(t)
((3, 1, 2), (2, 1), (1,))
sage: B.from_tableau(t) == b
True

val(q='q')

Return the $$Val$$ polynomial corresponding to self.

EXAMPLES:

Verifying Example 4.5 from [BCHOPSY2017]:

sage: B = crystals.Minimaj(3, 4, 2) # for Val_{4,1}^{(3)}
sage: B.val()
(q^2+q+1)*s[2, 1, 1] + q*s[2, 2]

class sage.combinat.multiset_partition_into_sets_ordered.OrderedMultisetPartitionIntoSets(parent, data)

Ordered Multiset Partition into sets

An ordered multiset partition into sets $$c$$ of a multiset $$X$$ is a list $$[c_1, \ldots, c_r]$$ of nonempty subsets of $$X$$ (note: not sub-multisets), called the blocks of $$c$$, whose multi-union is $$X$$.

EXAMPLES:

The simplest way to create an ordered multiset partition into sets is by specifying its blocks as a list or tuple:

sage: OrderedMultisetPartitionIntoSets([[3],[2,1]])
[{3}, {1,2}]
sage: OrderedMultisetPartitionIntoSets(((3,), (1,2)))
[{3}, {1,2}]
sage: OrderedMultisetPartitionIntoSets([set([i]) for i in range(2,5)])
[{2}, {3}, {4}]


REFERENCES:

check()

Check that we are a valid ordered multiset partition into sets.

EXAMPLES:

sage: c = OrderedMultisetPartitionsIntoSets(4)([[1], [1,2]])
sage: c.check()

sage: OMPs = OrderedMultisetPartitionsIntoSets()
sage: c = OMPs([[1], [1], ['a']])
sage: c.check()

deconcatenate(k=2)

Return the list of $$k$$-deconcatenations of self.

A $$k$$-tuple $$(C_1, \ldots, C_k)$$ of ordered multiset partitions into sets represents a $$k$$-deconcatenation of an ordered multiset partition into sets $$C$$ if $$C_1 + \cdots + C_k = C$$.

Note

This is not to be confused with self.split_blocks(), which splits each block of self before making $$k$$-tuples of ordered multiset partitions into sets.

EXAMPLES:

sage: OrderedMultisetPartitionIntoSets([[7,1],[3,4,5]]).deconcatenate()
[([{1,7}, {3,4,5}], []), ([{1,7}], [{3,4,5}]), ([], [{1,7}, {3,4,5}])]
sage: OrderedMultisetPartitionIntoSets([['b','c'],['a']]).deconcatenate()
[([{'b','c'}, {'a'}], []), ([{'b','c'}], [{'a'}]), ([], [{'b','c'}, {'a'}])]
sage: OrderedMultisetPartitionIntoSets([['a','b','c']]).deconcatenate(3)
[([{'a','b','c'}], [], []),
([], [{'a','b','c'}], []),
([], [], [{'a','b','c'}])]

fatten(grouping)

Return the ordered multiset partition into sets fatter than self, obtained by grouping together consecutive parts according to grouping (whenever this does not violate the strictness condition).

INPUT:

• grouping – a composition (or list) whose sum is the length of self

EXAMPLES:

Let us start with the composition:

sage: C = OrderedMultisetPartitionIntoSets([[4,1,5], [2], [7,1]]); C
[{1,4,5}, {2}, {1,7}]


With grouping equal to $$(1, 1, 1)$$, $$C$$ is left unchanged:

sage: C.fatten([1,1,1])
[{1,4,5}, {2}, {1,7}]


With grouping equal to $$(2,1)$$ or $$(1,2)$$, a union of consecutive parts is achieved:

sage: C.fatten([2,1])
[{1,2,4,5}, {1,7}]
sage: C.fatten([1,2])
[{1,4,5}, {1,2,7}]


However, the grouping $$(3)$$ will throw an error, as $$1$$ cannot appear twice in any block of C:

sage: C.fatten(Composition([3]))
Traceback (most recent call last):
...
ValueError: [{1,4,5,2,1,7}] is not a valid ordered multiset partition into sets

fatter()

Return the set of ordered multiset partitions into sets which are fatter than self.

An ordered multiset partition into sets $$A$$ is fatter than another $$B$$ if, reading left-to-right, every block of $$A$$ is the union of some consecutive blocks of $$B$$.

EXAMPLES:

sage: C = OrderedMultisetPartitionIntoSets([{1,4,5}, {2}, {1,7}]).fatter()
sage: len(C)
3
sage: sorted(C)
[[{1,4,5}, {2}, {1,7}], [{1,4,5}, {1,2,7}], [{1,2,4,5}, {1,7}]]
sage: sorted(OrderedMultisetPartitionIntoSets([['a','b'],['c'],['a']]).fatter())
[[{'a','b'}, {'c'}, {'a'}], [{'a','b'}, {'a','c'}], [{'a','b','c'}, {'a'}]]


Some extreme cases:

sage: list(OrderedMultisetPartitionIntoSets([['a','b','c']]).fatter())
[[{'a','b','c'}]]
sage: list(OrderedMultisetPartitionIntoSets([]).fatter())
[[]]
sage: A = OrderedMultisetPartitionIntoSets([[1], [2], [3], [4]])
sage: B = OrderedMultisetPartitionIntoSets([[1,2,3,4]])
sage: A.fatter().issubset(B.finer())
True

finer(strong=False)

Return the set of ordered multiset partitions into sets that are finer than self.

An ordered multiset partition into sets $$A$$ is finer than another $$B$$ if, reading left-to-right, every block of $$B$$ is the union of some consecutive blocks of $$A$$.

If optional argument strong is set to True, then return only those $$A$$ whose blocks are deconcatenations of blocks of $$B$$. (Here, we view blocks of $$B$$ as sorted lists instead of sets.)

EXAMPLES:

sage: C = OrderedMultisetPartitionIntoSets([[3,2]]).finer()
sage: len(C)
3
sage: sorted(C, key=str)
[[{2,3}], [{2}, {3}], [{3}, {2}]]
sage: OrderedMultisetPartitionIntoSets([]).finer()
{[]}
sage: O = OrderedMultisetPartitionsIntoSets([1, 1, 'a', 'b'])
sage: o = O([{1}, {'a', 'b'}, {1}])
sage: sorted(o.finer(), key=str)
[[{1}, {'a','b'}, {1}], [{1}, {'a'}, {'b'}, {1}], [{1}, {'b'}, {'a'}, {1}]]
sage: o.finer() & o.fatter() == set([o])
True

is_finer(co)

Return True if the ordered multiset partition into sets self is finer than the composition co; otherwise, return False.

EXAMPLES:

sage: OrderedMultisetPartitionIntoSets([[4],[1],[2]]).is_finer([[1,4],[2]])
True
sage: OrderedMultisetPartitionIntoSets([[1],[4],[2]]).is_finer([[1,4],[2]])
True
sage: OrderedMultisetPartitionIntoSets([[1,4],[1],[1]]).is_finer([[1,4],[2]])
False

length()

Return the number of blocks of self.

EXAMPLES:

sage: OrderedMultisetPartitionIntoSets([[7,1],[3]]).length()
2

letters()

Return the set of distinct elements occurring within the blocks of self.

EXAMPLES:

sage: C = OrderedMultisetPartitionIntoSets([[3, 4, 1], [2], [1, 2, 3, 7]]); C
[{1,3,4}, {2}, {1,2,3,7}]
sage: C.letters()
frozenset({1, 2, 3, 4, 7})

major_index()

Return the major index of self.

The major index is a statistic on ordered multiset partitions into sets, which we define here via an example.

1. Sort each block in the list self in descending order to create a word $$w$$, keeping track of the original separation into blocks:

in:  [{3,4,5}, {2,3,4}, {1}, {4,5}]
out: [ 5,4,3 /  4,3,2 /  1 /  5,4 ]

2. Create a sequence $$v = (v_0, v_1, v_2, \ldots)$$ of length self.order()+1, built recursively by:

1. $$v_0 = 0$$

2. $$v_j = v_{j-1} + \delta(j)$$, where $$\delta(j) = 1$$ if $$j$$ is the index of an end of a block, and zero otherwise.

in:    [ 5,4,3 /  4,3,2 /  1 /  5,4]
out: (0, 0,0,1,   1,1,2,   3,   3,4)

3. Compute $$\sum_j v_j$$, restricted to descent positions in $$w$$, i.e., sum over those $$j$$ with $$w_j > w_{j+1}$$:

in:  w:   [5, 4, 3, 4, 3, 2, 1, 5, 4]
v: (0 0, 0, 1, 1, 1, 2, 3, 3, 4)
maj :=     0 +0    +1 +1 +2    +3     = 7


REFERENCES:

EXAMPLES:

sage: C = OrderedMultisetPartitionIntoSets([{1,5,7}, {2,4}, {5,6}, {4,6,8}, {1,3}, {1,2,3}])
sage: C.major_index()
27
sage: C = OrderedMultisetPartitionIntoSets([{3,4,5}, {2,3,4}, {1}, {4,5}])
sage: C.major_index()
7

max_letter()

Return the maximum letter appearing in self.letters() of self.

EXAMPLES:

sage: C = OrderedMultisetPartitionIntoSets([[3, 4, 1], [2], [1, 2, 3, 7]])
sage: C.max_letter()
7
sage: D = OrderedMultisetPartitionIntoSets([['a','b','c'],['a','b'],['a'],['b','c','f'],['c','d']])
sage: D.max_letter()
'f'
sage: C = OrderedMultisetPartitionIntoSets([])
sage: C.max_letter()

minimaj()

Return the minimaj statistic on ordered multiset partitions into sets.

We define $$minimaj$$ via an example:

1. Sort the block in self as prescribed by self.minimaj_word(), keeping track of the original separation into blocks:

in:   [{1,5,7}, {2,4}, {5,6}, {4,6,8}, {1,3}, {1,2,3}]
out:  ( 5,7,1 /  2,4 /  5,6 /  4,6,8 /  3,1 /  1,2,3 )

2. Record the indices where descents in this word occur:

word:      (5, 7, 1 / 2, 4 / 5, 6 / 4, 6, 8 / 3, 1 / 1, 2, 3)
indices:    1  2  3   4  5   6  7   8  9 10  11 12  13 14 15
descents:  {   2,               7,       10, 11             }

3. Compute the sum of the descents:

minimaj = 2 + 7 + 10 + 11 = 30


REFERENCES:

EXAMPLES:

sage: C = OrderedMultisetPartitionIntoSets([{1,5,7}, {2,4}, {5,6}, {4,6,8}, {1,3}, {1,2,3}])
sage: C, C.minimaj_word()
([{1,5,7}, {2,4}, {5,6}, {4,6,8}, {1,3}, {1,2,3}],
(5, 7, 1, 2, 4, 5, 6, 4, 6, 8, 3, 1, 1, 2, 3))
sage: C.minimaj()
30
sage: C = OrderedMultisetPartitionIntoSets([{2,4}, {1,2,3}, {1,6,8}, {2,3}])
sage: C, C.minimaj_word()
([{2,4}, {1,2,3}, {1,6,8}, {2,3}], (2, 4, 1, 2, 3, 6, 8, 1, 2, 3))
sage: C.minimaj()
9
sage: OrderedMultisetPartitionIntoSets([]).minimaj()
0
sage: C = OrderedMultisetPartitionIntoSets([['b','d'],['a','b','c'],['b']])
sage: C, C.minimaj_word()
([{'b','d'}, {'a','b','c'}, {'b'}], ('d', 'b', 'c', 'a', 'b', 'b'))
sage: C.minimaj()
4

minimaj_blocks()

Return the minimaj ordering on blocks of self.

We define the ordering via the example below.

Sort the blocks $$[B_1,...,B_k]$$ of self from right to left via:

1. Sort the last block $$B_k$$ in increasing order, call it the word $$W_k$$

2. If blocks $$B_{i+1}, \ldots, B_k$$ have been converted to words $$W_{i+1}, \ldots, W_k$$, use the letters in $$B_i$$ to make the unique word $$W_i$$ that has a factorization $$W_i = (u, v)$$ satisfying:

• letters of $$u$$ and $$v$$ appear in increasing order, with $$v$$ possibly empty;

• letters in $$vu$$ appear in increasing order;

• v[-1] is the largest letter $$a \in B_i$$ satisfying a <= W_{i+1}[0].

EXAMPLES:

sage: OrderedMultisetPartitionIntoSets([[1,5,7], [2,4], [5,6], [4,6,8], [1,3], [1,2,3]])
[{1,5,7}, {2,4}, {5,6}, {4,6,8}, {1,3}, {1,2,3}]
sage: _.minimaj_blocks()
((5, 7, 1), (2, 4), (5, 6), (4, 6, 8), (3, 1), (1, 2, 3))
sage: OrderedMultisetPartitionIntoSets([]).minimaj_blocks()
()

minimaj_word()

Return an ordering of self._multiset derived from the minimaj ordering on blocks of self.

EXAMPLES:

sage: C = OrderedMultisetPartitionIntoSets([[2,1], [1,2,3], [1,2], [3], [1]]); C
[{1,2}, {1,2,3}, {1,2}, {3}, {1}]
sage: C.minimaj_blocks()
((1, 2), (2, 3, 1), (1, 2), (3,), (1,))
sage: C.minimaj_word()
(1, 2, 2, 3, 1, 1, 2, 3, 1)

multiset(as_dict=False)

Return the multiset corresponding to self.

INPUT:

• as_dict – (default: False) whether to return the multiset as a tuple of a dict of multiplicities

EXAMPLES:

sage: C = OrderedMultisetPartitionIntoSets([[3, 4, 1], [2], [1, 2, 3, 7]]); C
[{1,3,4}, {2}, {1,2,3,7}]
sage: C.multiset()
(1, 1, 2, 2, 3, 3, 4, 7)
sage: C.multiset(as_dict=True)
{1: 2, 2: 2, 3: 2, 4: 1, 7: 1}
sage: OrderedMultisetPartitionIntoSets([]).multiset() == ()
True

order()

Return the total number of elements in all blocks of self.

EXAMPLES:

sage: C = OrderedMultisetPartitionIntoSets([[3, 4, 1], [2], [1, 2, 3, 7]]); C
[{1,3,4}, {2}, {1,2,3,7}]
sage: C.order()
8
sage: C.order() == sum(C.weight().values())
True
sage: C.order() == sum(k for k in C.shape_from_cardinality())
True
sage: OrderedMultisetPartitionIntoSets([[7,1],[3]]).order()
3

reversal()

Return the reverse ordered multiset partition into sets of self.

Given an ordered multiset partition into sets $$(B_1, B_2, \ldots, B_k)$$, its reversal is defined to be the ordered multiset partition into sets $$(B_k, \ldots, B_2, B_1)$$.

EXAMPLES:

sage: C = OrderedMultisetPartitionIntoSets([[1], [1, 3], [2, 3, 4]]); C
[{1}, {1,3}, {2,3,4}]
sage: C.reversal()
[{2,3,4}, {1,3}, {1}]

shape_from_cardinality()

Return a composition that records the cardinality of each block of self.

EXAMPLES:

sage: C = OrderedMultisetPartitionIntoSets([[3, 4, 1], [2], [1, 2, 3, 7]]); C
[{1,3,4}, {2}, {1,2,3,7}]
sage: C.shape_from_cardinality()
[3, 1, 4]
sage: OrderedMultisetPartitionIntoSets([]).shape_from_cardinality() == Composition([])
True

shape_from_size()

Return a composition that records the sum of entries of each block of self.

EXAMPLES:

sage: C = OrderedMultisetPartitionIntoSets([[3, 4, 1], [2], [1, 2, 3, 7]]); C
[{1,3,4}, {2}, {1,2,3,7}]
sage: C.shape_from_size()
[8, 2, 13]

shuffle_product(other, overlap=False)

Return the shuffles (with multiplicity) of blocks of self with blocks of other.

In case optional argument overlap is True, instead return the allowable overlapping shuffles. An overlapping shuffle $$C$$ is allowable if, whenever one of its blocks $$c$$ comes from the union $$c = a \cup b$$ of a block of self and a block of other, then this union is disjoint.

EXAMPLES:

sage: A = OrderedMultisetPartitionIntoSets([[2,1,3], [1,2]]); A
[{1,2,3}, {1,2}]
sage: B = OrderedMultisetPartitionIntoSets([[3,4]]); B
[{3,4}]
sage: C = OrderedMultisetPartitionIntoSets([[4,5]]); C
[{4,5}]
sage: list(A.shuffle_product(B))
[[{1,2,3}, {1,2}, {3,4}], [{3,4}, {1,2,3}, {1,2}], [{1,2,3}, {3,4}, {1,2}]]
sage: list(A.shuffle_product(B, overlap=True))
[[{1,2,3}, {1,2}, {3,4}], [{1,2,3}, {3,4}, {1,2}],
[{3,4}, {1,2,3}, {1,2}], [{1,2,3}, {1,2,3,4}]]
sage: list(A.shuffle_product(C, overlap=True))
[[{1,2,3}, {1,2}, {4,5}], [{1,2,3}, {4,5}, {1,2}], [{4,5}, {1,2,3}, {1,2}],
[{1,2,3,4,5}, {1,2}], [{1,2,3}, {1,2,4,5}]]

size()

Return the size of self (that is, the sum of all integers in all blocks) if self is a list of subsets of positive integers.

Else, return None.

EXAMPLES:

sage: C = OrderedMultisetPartitionIntoSets([[3, 4, 1], [2], [1, 2, 3, 7]]); C
[{1,3,4}, {2}, {1,2,3,7}]
sage: C.size()
23
sage: C.size() == sum(k for k in C.shape_from_size())
True
sage: OrderedMultisetPartitionIntoSets([[7,1],[3]]).size()
11

split_blocks(k=2)

Return a dictionary representing the $$k$$-splittings of self.

A $$k$$-tuple $$(A^1, \ldots, A^k)$$ of ordered multiset partitions into sets represents a $$k$$-splitting of an ordered multiset partition into sets $$A = [b_1, \ldots, b_r]$$ if one can express each block $$b_i$$ as an (ordered) disjoint union of sets $$b_i = b^1_i \sqcup \cdots \sqcup b^k_i$$ (some possibly empty) so that each $$A^j$$ is the ordered multiset partition into sets corresponding to the list $$[b^j_1, b^j_2, \ldots, b^j_r]$$, excising empty sets appearing therein.

This operation represents the coproduct in Hopf algebra of ordered multiset partitions into sets in its natural basis [LM2018].

EXAMPLES:

sage: sorted(OrderedMultisetPartitionIntoSets([[1,2],[3,4]]).split_blocks(), key=str)
[([], [{1,2}, {3,4}]),
([{1,2}, {3,4}], []),
([{1,2}, {3}], [{4}]),
([{1,2}, {4}], [{3}]),
([{1,2}], [{3,4}]),
([{1}, {3,4}], [{2}]),
([{1}, {3}], [{2}, {4}]),
([{1}, {4}], [{2}, {3}]),
([{1}], [{2}, {3,4}]),
([{2}, {3,4}], [{1}]),
([{2}, {3}], [{1}, {4}]),
([{2}, {4}], [{1}, {3}]),
([{2}], [{1}, {3,4}]),
([{3,4}], [{1,2}]),
([{3}], [{1,2}, {4}]),
([{4}], [{1,2}, {3}])]
sage: sorted(OrderedMultisetPartitionIntoSets([[1,2]]).split_blocks(3), key=str)
[([], [], [{1,2}]), ([], [{1,2}], []), ([], [{1}], [{2}]),
([], [{2}], [{1}]), ([{1,2}], [], []), ([{1}], [], [{2}]),
([{1}], [{2}], []), ([{2}], [], [{1}]), ([{2}], [{1}], [])]
sage: OrderedMultisetPartitionIntoSets([[4],[4]]).split_blocks()
{([], [{4}, {4}]): 1, ([{4}], [{4}]): 2, ([{4}, {4}], []): 1}

to_tableaux_words()

Return a sequence of lists corresponding to row words of (skew-)tableaux.

OUTPUT:

The minimaj bijection $$\phi$$ of [BCHOPSY2017] applied to self.

Todo

Implement option for mapping to sequence of (skew-)tableaux?

EXAMPLES:

sage: co = ((1,2,4),(4,5),(3,),(4,6,1),(2,3,1),(1,),(2,5))
sage: OrderedMultisetPartitionIntoSets(co).to_tableaux_words()
[[5, 1], [3, 1], [6], [5, 4, 2], [1, 4, 3, 4, 2, 1, 2]]

weight(as_weak_comp=False)

Return a dictionary, with keys being the letters in self.letters() and values being their (positive) frequency.

Alternatively, if as_weak_comp is True, count the number of instances $$n_i$$ for each distinct positive integer $$i$$ across all blocks of self. Return as a list $$[n_1, n_2, n_3, ..., n_k]$$, where $$k$$ is the max letter appearing in self.letters().

EXAMPLES:

sage: c = OrderedMultisetPartitionIntoSets([[6,1],[1,3],[1,3,6]])
sage: c.weight()
{1: 3, 3: 2, 6: 2}
sage: c.weight(as_weak_comp=True)
[3, 0, 2, 0, 0, 2]

class sage.combinat.multiset_partition_into_sets_ordered.OrderedMultisetPartitionsIntoSets(is_finite=None, **constraints)

Ordered Multiset Partitions into Sets.

An ordered multiset partition into sets $$c$$ of a multiset $$X$$ is a list of nonempty subsets (not multisets), called the blocks of $$c$$, whose multi-union is $$X$$.

The number of blocks of $$c$$ is called its length. The order of $$c$$ is the cardinality of the multiset $$X$$. If, additionally, $$X$$ is a multiset of positive integers, then the size of $$c$$ is the sum of all elements of $$X$$.

The user may wish to focus on ordered multiset partitions into sets of a given size, or over a given alphabet. Hence, this class allows a variety of arguments as input.

INPUT:

Expects one or two arguments, with different behaviors resulting:

• One Argument:

• $$X$$ – a dictionary or list or tuple (representing a multiset for $$c$$), or an integer (representing the size of $$c$$)

• Two Arguments:

• $$A$$ – a list (representing allowable letters within blocks of $$c$$), or a positive integer (representing the maximal allowable letter)

• $$n$$ – a nonnegative integer (the total number of letters within $$c$$)

Optional keyword arguments are as follows: (See corresponding methods in see OrderedMultisetPartitionIntoSets for more details.)

• weight=X (list or dictionary $$X$$) specifies the multiset for $$c$$

• size=n (integer $$n$$) specifies the size of $$c$$

• alphabet=A (iterable $$A$$) specifies allowable elements for the blocks of $$c$$

• length=k (integer $$k$$) specifies the number of blocks in the partition

• min_length=k (integer $$k$$) specifies minimum number of blocks in the partition

• max_length=k (integer $$k$$) specifies maximum number of blocks in the partition

• order=n (integer $$n$$) specifies the cardinality of the multiset that $$c$$ partitions

• min_order=n (integer $$n$$) specifies minimum number of elements in the partition

• max_order=n (integer $$n$$) specifies maximum number of elements in the partition

EXAMPLES:

Passing one argument to OrderedMultisetPartitionsIntoSets:

There are 5 ordered multiset partitions into sets of the multiset $$\{\{1, 1, 4\}\}$$:

sage: OrderedMultisetPartitionsIntoSets([1,1,4]).cardinality()
5


Here is the list of them:

sage: OrderedMultisetPartitionsIntoSets([1,1,4]).list()
[[{1}, {1}, {4}], [{1}, {1,4}], [{1}, {4}, {1}], [{1,4}, {1}], [{4}, {1}, {1}]]


By chance, there are also 5 ordered multiset partitions into sets of the integer 3:

sage: OrderedMultisetPartitionsIntoSets(3).cardinality()
5


Here is the list of them:

sage: OrderedMultisetPartitionsIntoSets(3).list()
[[{3}], [{1,2}], [{2}, {1}], [{1}, {2}], [{1}, {1}, {1}]]


Passing two arguments to OrderedMultisetPartitionsIntoSets:

There are also 5 ordered multiset partitions into sets of order 2 over the alphabet $$\{1, 4\}$$:

sage: OrderedMultisetPartitionsIntoSets([1, 4], 2)
Ordered Multiset Partitions into Sets of order 2 over alphabet {1, 4}
sage: OrderedMultisetPartitionsIntoSets([1, 4], 2).cardinality()
5


Here is the list of them:

sage: OrderedMultisetPartitionsIntoSets([1, 4], 2).list()
[[{1,4}], [{1}, {1}], [{1}, {4}], [{4}, {1}], [{4}, {4}]]


If no arguments are passed to OrderedMultisetPartitionsIntoSets, then the code returns all ordered multiset partitions into sets:

sage: OrderedMultisetPartitionsIntoSets()
Ordered Multiset Partitions into Sets
sage: [] in OrderedMultisetPartitionsIntoSets()
True
sage: [[2,3], [1]] in OrderedMultisetPartitionsIntoSets()
True
sage: [['a','b'], ['a']] in OrderedMultisetPartitionsIntoSets()
True
sage: [[-2,3], [3]] in OrderedMultisetPartitionsIntoSets()
True
sage: [[2], [3,3]] in OrderedMultisetPartitionsIntoSets()
False


The following examples show how to test whether or not an object is an ordered multiset partition into sets:

sage: [[3,2],[2]] in OrderedMultisetPartitionsIntoSets()
True
sage: [[3,2],[2]] in OrderedMultisetPartitionsIntoSets(7)
True
sage: [[3,2],[2]] in OrderedMultisetPartitionsIntoSets([2,2,3])
True
sage: [[3,2],[2]] in OrderedMultisetPartitionsIntoSets(5)
False


Optional keyword arguments

Passing keyword arguments that are incompatible with required requirements results in an error; otherwise, the collection of ordered multiset partitions into sets is restricted accordingly:

The weight keyword:

This is used to specify which multiset $$X$$ is to be considered, if this multiset was not passed as one of the required arguments for OrderedMultisetPartitionsIntoSets. In principle, it is a dictionary, but weak compositions are also allowed. For example, the ordered multiset partitions into sets of integer 4 are listed by weight below:

sage: OrderedMultisetPartitionsIntoSets(4, weight=[0,0,0,1])
Ordered Multiset Partitions into Sets of integer 4 with constraint: weight={4: 1}
sage: OrderedMultisetPartitionsIntoSets(4, weight=[0,0,0,1]).list()
[[{4}]]
sage: OrderedMultisetPartitionsIntoSets(4, weight=[1,0,1]).list()
[[{1}, {3}], [{1,3}], [{3}, {1}]]
sage: OrderedMultisetPartitionsIntoSets(4, weight=[0,2]).list()
[[{2}, {2}]]
sage: OrderedMultisetPartitionsIntoSets(4, weight=[0,1,1]).list()
[]
sage: OrderedMultisetPartitionsIntoSets(4, weight=[2,1]).list()
[[{1}, {1}, {2}], [{1}, {1,2}], [{1}, {2}, {1}], [{1,2}, {1}], [{2}, {1}, {1}]]
sage: O1 = OrderedMultisetPartitionsIntoSets(weight=[2,0,1])
sage: O2 = OrderedMultisetPartitionsIntoSets(weight={1:2, 3:1})
sage: O1 == O2
True
sage: OrderedMultisetPartitionsIntoSets(4, weight=[4]).list()
[[{1}, {1}, {1}, {1}]]


The size keyword:

This is used to constrain the sum of entries across all blocks of the ordered multiset partition into sets. (This size is not pre-determined when alphabet $$A$$ and order $$d$$ are passed as required arguments.) For example, the ordered multiset partitions into sets of order 3 over the alphabet $$[1,2,4]$$ that have size equal to 5 are as follows:

sage: OMPs = OrderedMultisetPartitionsIntoSets
sage: OMPs([1,2,4], 3, size=5).list()
[[{1,2}, {2}], [{2}, {1,2}], [{2}, {2}, {1}],
[{2}, {1}, {2}], [{1}, {2}, {2}]]


The alphabet option:

This is used to constrain which integers appear across all blocks of the ordered multiset partition into sets. For example, the ordered multiset partitions into sets of integer 4 are listed for different choices of alphabet below. Note that alphabet is allowed to be an integer or an iterable:

sage: OMPs = OrderedMultisetPartitionsIntoSets
sage: OMPs(4, alphabet=3).list()
[[{1,3}], [{3}, {1}],
[{1,2}, {1}], [{2}, {2}],
[{2}, {1}, {1}], [{1}, {3}],
[{1}, {1,2}], [{1}, {2}, {1}],
[{1}, {1}, {2}], [{1}, {1}, {1}, {1}]]
sage: OMPs(4, alphabet=3) == OMPs(4, alphabet=[1,2,3])
True
sage: OMPs(4, alphabet=[3]).list()
[]
sage: OMPs(4, alphabet=[1,3]).list()
[[{1,3}], [{3}, {1}], [{1}, {3}], [{1}, {1}, {1}, {1}]]
sage: OMPs(4, alphabet=[2]).list()
[[{2}, {2}]]
sage: OMPs(4, alphabet=[1,2]).list()
[[{1,2}, {1}], [{2}, {2}], [{2}, {1}, {1}], [{1}, {1,2}],
[{1}, {2}, {1}], [{1}, {1}, {2}], [{1}, {1}, {1}, {1}]]
sage: OMPs(4, alphabet=4).list() == OMPs(4).list()
True


The length, min_length, and max_length options:

These are used to constrain the number of blocks within the ordered multiset partitions into sets. For example, the ordered multiset partitions into sets of integer 4 of length exactly 2, at least 2, and at most 2 are given by:

sage: OrderedMultisetPartitionsIntoSets(4, length=2).list()
[[{3}, {1}], [{1,2}, {1}], [{2}, {2}], [{1}, {3}], [{1}, {1,2}]]
sage: OrderedMultisetPartitionsIntoSets(4, min_length=3).list()
[[{2}, {1}, {1}], [{1}, {2}, {1}], [{1}, {1}, {2}], [{1}, {1}, {1}, {1}]]
sage: OrderedMultisetPartitionsIntoSets(4, max_length=2).list()
[[{4}], [{1,3}], [{3}, {1}], [{1,2}, {1}], [{2}, {2}], [{1}, {3}],
[{1}, {1,2}]]


The order, min_order, and max_order options:

These are used to constrain the number of elements across all blocks of the ordered multiset partitions into sets. For example, the ordered multiset partitions into sets of integer 4 are listed by order below:

sage: OrderedMultisetPartitionsIntoSets(4, order=1).list()
[[{4}]]
sage: OrderedMultisetPartitionsIntoSets(4, order=2).list()
[[{1,3}], [{3}, {1}], [{2}, {2}], [{1}, {3}]]
sage: OrderedMultisetPartitionsIntoSets(4, order=3).list()
[[{1,2}, {1}], [{2}, {1}, {1}], [{1}, {1,2}], [{1}, {2}, {1}], [{1}, {1}, {2}]]
sage: OrderedMultisetPartitionsIntoSets(4, order=4).list()
[[{1}, {1}, {1}, {1}]]


Also, here is a use of max_order, giving the ordered multiset partitions into sets of integer 4 with order 1 or 2:

sage: OrderedMultisetPartitionsIntoSets(4, max_order=2).list()
[[{4}], [{1,3}], [{3}, {1}], [{2}, {2}], [{1}, {3}]]

Element
subset(size)

Return a subset of all ordered multiset partitions into sets.

INPUT:

• size – an integer representing a slice of all ordered multiset partitions into sets

The slice alluded to above is taken with respect to length, or to order, or to size, depending on the constraints of self.

EXAMPLES:

sage: C = OrderedMultisetPartitionsIntoSets(weight={2:2, 3:1, 5:1})
sage: C.subset(3)
Ordered Multiset Partitions into Sets of multiset {{2, 2, 3, 5}} with constraint: length=3
sage: C = OrderedMultisetPartitionsIntoSets(weight={2:2, 3:1, 5:1}, min_length=2)
sage: C.subset(3)
Ordered Multiset Partitions into Sets of multiset {{2, 2, 3, 5}} with constraint: length=3
sage: C = OrderedMultisetPartitionsIntoSets(alphabet=[2,3,5])
sage: C.subset(3)
Ordered Multiset Partitions into Sets of order 3 over alphabet {2, 3, 5}
sage: C = OrderedMultisetPartitionsIntoSets(order=5)
sage: C.subset(3)
Ordered Multiset Partitions into Sets of integer 3 with constraint: order=5
sage: C = OrderedMultisetPartitionsIntoSets(alphabet=[2,3,5], order=5, length=3)
sage: C.subset(3)
Ordered Multiset Partitions into Sets of order 3 over alphabet {2, 3, 5} with constraint: length=3
sage: C = OrderedMultisetPartitionsIntoSets()
sage: C.subset(3)
Ordered Multiset Partitions into Sets of integer 3
sage: C.subset(3) == OrderedMultisetPartitionsIntoSets(3)
True

class sage.combinat.multiset_partition_into_sets_ordered.OrderedMultisetPartitionsIntoSets_X(X)

Class of ordered multiset partitions into sets of a fixed multiset $$X$$.

cardinality()

Return the number of ordered partitions of multiset X.

random_element()

Return a random element of self.

This method does not return elements of self with uniform probability, but it does cover all elements. The scheme is as follows:

• produce a random permutation p of the multiset;

• create blocks of an OMP fat by breaking p after non-ascents;

• take a random element of fat.finer().

EXAMPLES:

sage: OrderedMultisetPartitionsIntoSets([1,1,3]).random_element()  # random
[{1}, {1,3}]
sage: OrderedMultisetPartitionsIntoSets([1,1,3]).random_element()  # random
[{3}, {1}, {1}]

sage: OMP = OrderedMultisetPartitionsIntoSets([1,1,3,3])
sage: d = {}
sage: for _ in range(1000):
....:     x = OMP.random_element()
....:     d[x] = d.get(x, 0) + 1
sage: d.values()  # random
[102, 25, 76, 24, 66, 88, 327, 27, 83, 83, 239, 72, 88]

class sage.combinat.multiset_partition_into_sets_ordered.OrderedMultisetPartitionsIntoSets_X_constraints(X, **constraints)

Class of ordered multiset partitions into sets of a fixed multiset $$X$$ satisfying constraints.

class sage.combinat.multiset_partition_into_sets_ordered.OrderedMultisetPartitionsIntoSets_all_constraints(is_finite=None, **constraints)

All ordered multiset partitions into sets (with or without constraints).

EXAMPLES:

sage: C = OrderedMultisetPartitionsIntoSets(); C
Ordered Multiset Partitions into Sets
sage: [[1],[1,'a']] in C
True

sage: OrderedMultisetPartitionsIntoSets(weight=[2,0,1], length=2)
Ordered Multiset Partitions into Sets of multiset {{1, 1, 3}} with constraint: length=2

class sage.combinat.multiset_partition_into_sets_ordered.OrderedMultisetPartitionsIntoSets_alph_d(A, d)

Class of ordered multiset partitions into sets of specified order $$d$$ over a fixed alphabet $$A$$.

cardinality()

Return the number of ordered partitions of order self._order on alphabet self._alphabet.

random_element()

Return a random element of self.

This method does not return elements of self with uniform probability, but it does cover all elements. The scheme is as follows:

• produce a random composition $$C$$;

• choose random subsets of self._alphabet of size $$c$$ for each $$c$$ in $$C$$.

EXAMPLES:

sage: OrderedMultisetPartitionsIntoSets([1,4], 3).random_element()  # random
[{4}, {1,4}]
sage: OrderedMultisetPartitionsIntoSets([1,3], 4).random_element()  # random
[{1,3}, {1}, {3}]

sage: OMP = OrderedMultisetPartitionsIntoSets([2,3,4], 2)
sage: d = {}
sage: for _ in range(1200):
....:     x = OMP.random_element()
....:     d[x] = d.get(x, 0) + 1
sage: d.values()  # random
[192, 68, 73, 61, 69, 60, 77, 204, 210, 66, 53, 67]

class sage.combinat.multiset_partition_into_sets_ordered.OrderedMultisetPartitionsIntoSets_alph_d_constraints(A, d, **constraints)

Class of ordered multiset partitions into sets of specified order $$d$$ over a fixed alphabet $$A$$ satisfying constraints.

class sage.combinat.multiset_partition_into_sets_ordered.OrderedMultisetPartitionsIntoSets_n(n)

Ordered multiset partitions into sets of a fixed integer $$n$$.

cardinality()

Return the number of elements in self.

random_element()

Return a random element of self.

This method does not return elements of self with uniform probability, but it does cover all elements. The scheme is as follows:

• produce a random composition $$C$$;

• choose a random partition of $$c$$ into distinct parts for each $$c$$ in $$C$$.

EXAMPLES:

sage: OrderedMultisetPartitionsIntoSets(5).random_element()  # random
[{1,2}, {1}, {1}]
sage: OrderedMultisetPartitionsIntoSets(5).random_element()  # random
[{2}, {1,2}]

sage: OMP = OrderedMultisetPartitionsIntoSets(5)
sage: d = {}
sage: for _ in range(1100):
....:     x = OMP.random_element()
....:     d[x] = d.get(x, 0) + 1
sage: d.values()  # random
[72, 73, 162, 78, 135, 75, 109, 65, 135, 134, 62]

class sage.combinat.multiset_partition_into_sets_ordered.OrderedMultisetPartitionsIntoSets_n_constraints(n, **constraints)

Class of ordered multiset partitions into sets of a fixed integer $$n$$ satisfying constraints.