Non-ambiguous trees: new results and generalization

Abstract

We present a new definition of non-ambiguous trees (NATs) as labelled binary trees. We thus get a differ- ential equation whose solution can be described combinatorially. This yield a new formula for the number of NATs. We also obtain q-versions of our formula. And we generalize NATs to higher dimension.

Keywords

• [math.math-co]mathematics [math]/combinatorics [math.co]