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LyndonWord examples
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A function f in [0,1] is called acyclic if C(F) consists of n
different objects. The canonical representative of the orbit of an
acyclic function is usually called a Lyndon Word. If f is acyclic,
then all elements in the orbit C(f) are acyclic as well, and we call
C(f) an acyclic orbit.

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Initialisations
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::

  a:Symbol :='a
    a
                            Type: Symbol

  b:Symbol :='b
    b
                            Type: Symbol

  c:Symbol :='c
    c
                            Type: Symbol

  lword:= LyndonWord(Symbol)
    LyndonWord Symbol
                            Type: Domain

  magma := Magma(Symbol)
    Magma Symbol
                            Type: Domain

  word := OrderedFreeMonoid(Symbol)
    OrderedFreeMonoid Symbol
                            Type: Domain

All Lyndon words of with a, b, c to order 3 ::

  LyndonWordsList1([a,b,c],3)$lword
   [[[a],[b],[c]], [[a b],[a c],[b c]],
       2     2       2                      2    2       2
    [[a b],[a c],[a b ],[a b c],[a c b],[a c ],[b c],[b c ]]]
                            Type: OneDimensionalArray List LyndonWord Symbol

All Lyndon words of with a, b, c to order 3 in flat list ::

  LyndonWordsList([a,b,c],3)$lword
                                          2      2        2
   [[a], [b], [c], [a b], [a c], [b c], [a b], [a c], [a b ], [a b c], [a c b],
        2     2        2
    [a c ], [b c], [b c ]]
                            Type: List LyndonWord Symbol

All Lyndon words of with a, b to order 5 ::

  lw := LyndonWordsList([a,b],5)$lword
                       2        2     3      2 2       3     4      3 2
   [[a], [b], [a b], [a b], [a b ], [a b], [a b ], [a b ], [a b], [a b ],
      2          2 3           2       4
    [a b a b], [a b ], [a b a b ], [a b ]]
                            Type: List LyndonWord Symbol

  w1 : word := lw.4 :: word
     2
    a b
                             Type: OrderedFreeMonoid Symbol

  w2 : word := lw.5 :: word
       2
    a b
                             Type: OrderedFreeMonoid Symbol

Let's try factoring ::

  factor(a::word)$lword
    [[a]]
                             Type: List LyndonWord Symbol

  factor(w1*w2)$lword
       2     2
    [[a b a b ]]
                             Type: List LyndonWord Symbol

  factor(w2*w2)$lword
         2      2
    [[a b ],[a b ]]
                             Type: List LyndonWord Symbol

  factor(w2*w1)$lword
         2    2
    [[a b ],[a b]]
                             Type: List LyndonWord Symbol

--------------------
Checks and coercions
--------------------

::

  lyndon?(w1)$lword
    true
                             Type: Boolean

  lyndon?(w1*w2)$lword
    true
                             Type: Boolean

  lyndon?(w2*w1)$lword
    false
                             Type: Boolean

  lyndonIfCan(w1)$lword
      2
    [a b]
                             Type: Union(LyndonWord Symbol,...)

  lyndonIfCan(w2*w1)$lword
    "failed"
                             Type: Union("failed",...)

  lyndon(w1)$lword
      2
    [a b]
                             Type: LyndonWord Symbol

  lyndon(w1*w2)$lword
      2     2
    [a b a b ]
                             Type: LyndonWord Symbol

See Also:

* )show LyndonWord