2 papers
math.CO2008
Pattern Avoidance in Generalized Non-crossing Trees
Yidong Sun, Zhiping Wang
In this paper, the problem of pattern avoidance in generalized non-crossing trees is studied. The generating functions for generalized non-crossing trees avoiding patterns of lengt…
math.CO2008
The Star of David Rule
Yidong Sun
In this note, a new concept called {\em -matrix} is proposed, which is an infinite lower triangular matrix obeying the generalized rule of David star. Some basic properties of…