Bases: sage.combinat.words.word.FiniteWord_list
Construction of a Lyndon word.
INPUT:
OUTPUT:
A Lyndon word.
EXAMPLES:
sage: LyndonWord([1,2,2])
word: 122
sage: LyndonWord([1,2,3])
word: 123
sage: LyndonWord([2,1,2,3])
Traceback (most recent call last):
...
ValueError: Not a Lyndon word
If check is False, then no verification is done:
sage: LyndonWord([2,1,2,3], check=False)
word: 2123
Returns the combinatorial class of Lyndon words.
A Lyndon word is a word that is lexicographically less than all of
its rotations. Equivalently, whenever
is split into two non-empty
substrings,
is lexicographically less than the right substring.
INPUT:
or
or
OUTPUT:
A combinatorial class of Lyndon words.
EXAMPLES:
sage: LyndonWords()
Lyndon words
If e is an integer, then e specifies the length of the alphabet; k must also be specified in this case:
sage: LW = LyndonWords(3,3); LW
Lyndon words from an alphabet of size 3 of length 3
sage: LW.first()
word: 112
sage: LW.last()
word: 233
sage: LW.random_element()
word: 112
sage: LW.cardinality()
8
If e is a (weak) composition, then it returns the class of Lyndon words that have evaluation e:
sage: LyndonWords([2, 0, 1]).list()
[word: 113]
sage: LyndonWords([2, 0, 1, 0, 1]).list()
[word: 1135, word: 1153, word: 1315]
sage: LyndonWords([2, 1, 1]).list()
[word: 1123, word: 1132, word: 1213]
Bases: sage.combinat.words.words.Words_all
TESTS:
sage: C = sage.combinat.combinat.CombinatorialClass()
sage: C.category()
Category of enumerated sets
sage: C.__class__
<class 'sage.combinat.combinat.CombinatorialClass_with_category'>
sage: isinstance(C, Parent)
True
sage: C = sage.combinat.combinat.CombinatorialClass(category = FiniteEnumeratedSets())
sage: C.category()
Category of finite enumerated sets
Bases: sage.combinat.combinat.CombinatorialClass
TESTS:
sage: LW21 = LyndonWords([2,1]); LW21
Lyndon words with evaluation [2, 1]
sage: LW21 == loads(dumps(LW21))
True
Returns the number of Lyndon words with the evaluation e.
EXAMPLES:
sage: LyndonWords([]).cardinality()
0
sage: LyndonWords([2,2]).cardinality()
1
sage: LyndonWords([2,3,2]).cardinality()
30
Check to make sure that the count matches up with the number of Lyndon words generated.
sage: comps = [[],[2,2],[3,2,7],[4,2]]+Compositions(4).list()
sage: lws = [ LyndonWords(comp) for comp in comps]
sage: all( [ lw.cardinality() == len(lw.list()) for lw in lws] )
True
Bases: sage.combinat.words.words.FiniteWords_length_k_over_OrderedAlphabet
TESTS:
sage: LW23 = LyndonWords(2,3); LW23
Lyndon words from an alphabet of size 2 of length 3
sage: LW23== loads(dumps(LW23))
True
TESTS:
sage: [ LyndonWords(3,i).cardinality() for i in range(1, 11) ]
[3, 3, 8, 18, 48, 116, 312, 810, 2184, 5880]
Returns the combinatorial class of standard bracketed Lyndon words from [1, ..., n] of length k. These are in one to one correspondence with the Lyndon words and form a basis for the subspace of degree k of the free Lie algebra of rank n.
EXAMPLES:
sage: SBLW33 = StandardBracketedLyndonWords(3,3); SBLW33
Standard bracketed Lyndon words from an alphabet of size 3 of length 3
sage: SBLW33.first()
[1, [1, 2]]
sage: SBLW33.last()
[[2, 3], 3]
sage: SBLW33.cardinality()
8
sage: SBLW33.random_element()
[1, [1, 2]]
Bases: sage.combinat.combinat.CombinatorialClass
TESTS:
sage: SBLW = StandardBracketedLyndonWords(3, 2)
sage: SBLW == loads(dumps(SBLW))
True
EXAMPLES:
sage: StandardBracketedLyndonWords(3, 3).cardinality()
8
sage: StandardBracketedLyndonWords(3, 4).cardinality()
18
Returns the standard bracketing of a Lyndon word lw.
EXAMPLES:
sage: import sage.combinat.lyndon_word as lyndon_word
sage: map( lyndon_word.standard_bracketing, LyndonWords(3,3) )
[[1, [1, 2]],
[1, [1, 3]],
[[1, 2], 2],
[1, [2, 3]],
[[1, 3], 2],
[[1, 3], 3],
[2, [2, 3]],
[[2, 3], 3]]