In mathematics, a lattice word (or lattice permutation) is a string composed of positive integers, in which every prefix contains at least as many positive integers i as integers i + 1. A reverse lattice word, or Yamanouchi word (named after Takahiko Yamanouchi), is a string whose reversal is a lattice word.
Examples For instance, 11122121 is a lattice permutation, so 12122111 is a Yamanouchi word, but 12122111 is not a lattice permutation, since the prefix 12122 contains more 2s than 1s.
See also Dyck word
References Fulton, William (1997), Young tableaux, London Mathematical Society Student Texts, vol. 35, Cambridge University Press, ISBN 978-0-521-56724-4, MR 1464693 Macdonald, Ian G. (1995), Symmetric functions and Hall polynomials, Oxford Mathematical Monographs (Second ed.), The Clarendon Press and Oxford University Press, ISBN 0-19-853489-2, MR 1354144
