We study the numbers M n, k r, s , N n, r k =M n, k r, r , N E (n, k, p), and N O (n, k, p), prove several simple relations among them, and derive a simpler formula for M n, k r, s than appears in .
Counting Pairs of Lattice Paths by Intersections
โ Scribed by Ira Gessel; Wayne Goddard; Walter Shur; Herbert S. Wilf; Lily Yen
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 377 KB
- Volume
- 74
- Category
- Article
- ISSN
- 0097-3165
No coin nor oath required. For personal study only.
โฆ Synopsis
We count the pairs of walks between diagonally opposite corners of a given lattice rectangle by the number of points in which they intersect. We note that the number of such pairs with one intersection is twice the number with no intersection and we give a bijective proof of that fact. Some probabilistic variants of the problem are also investigated.
๐ SIMILAR VOLUMES
This formula was proved in [2] by means of generating functions. ## 2. INTERPRETATION OF THE FORMULA'S SUMMANDS Our bijection is based on an appropriate lattice-path-interpretation for the formula's summands (pointed out by Krattenthaler [4]): Clearly, we article no. TA962754 154 0097-3165ร97 25.0