34.5 Operations for Associative Words by their Syllables

For an associative word w = x1n1 x2n2 ¼xknk over an alphabet containing x1, x2, ¼, xk, such that xi ¹ xi+1±1 for 1 £ i £ k-1, the subwords xiei are uniquely determined; these powers of generators are called the syllables of w.

  • NumberSyllables( w ) A

    NumberSyllables returns the number of syllables of the associative word w.

  • ExponentSyllable( w, i ) O

    ExponentSyllable returns the exponent of the i-th syllable of the associative word w.

  • GeneratorSyllable( w, i ) O

    GeneratorSyllable returns the number of the generator that is involved in the i-th syllable of the associative word w.

  • SubSyllables( w, from, to ) O

    SubSyllables returns the subword of the associative word w that consists of the syllables from positions from to to, where from and to must be positive integers, and indexing is done with origin 1.

    gap> w;  NumberSyllables( w );
    a^5*b*a^2*b^-4*a
    5
    gap> ExponentSyllable( w, 3 );
    2
    gap> GeneratorSyllable( w, 3 );
    1
    gap> SubSyllables( w, 2, 3 );
    b*a^2
    

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    GAP 4 manual
    February 2000