OFFSET
1,3
COMMENTS
A bifix (sometimes biprefix) code is a set of nonempty words X such that no word of X is a proper prefix or a proper suffix of another. The degree of a finite maximal bifix code X is the maximal number of parses that a word can have with respect to X.
It is known that there are finitely many finite maximal bifix codes of each degree.
REFERENCES
J. Berstel and D. Perrin, Theory of Codes, Academic Press, 1985, Chapter III.
EXAMPLE
On the alphabet {a,b}, for n=3 the a(3)=3 codes are:
{aaa,aab,aba,abb,baa,bab,bba,bbb},
{aaa,aaba,aabb,ab,baa,baba,babb,bba,bbb},
{aaa,aab,abaa,abab,abb,ba,bbaa,bbab,bbb}
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Alessandro De Luca, Feb 09 2011
STATUS
approved