%0 Journal Article
%T Some simple bijections involving lattice walks and ballot sequences
%A Marc A. A. Van Leeuwen
%J Mathematics
%D 2010
%I arXiv
%X In this note we observe that a bijection related to Littelmann's root operators (for type $A_1$) transparently explains the well known enumeration by length of walks on $\N$ (left factors of Dyck paths), as well as some other enumerative coincidences. We indicate a relation with bijective solutions of Bertrand's ballot problem: those can be mechanically transformed into bijective proofs of the mentioned enumeration formula.
%U http://arxiv.org/abs/1010.4847v1