In this paper we examine the problem of reconstructing a discrete two-dimensional set from its two orthogonal projection (H, V ) when the set satisfies some convexity conditions. We show that the algorithm of the paper [Int. J. Imaging Systems and Technol. 9 (1998) 69] is a good heuristic algorithm but it does not solve the problem for all (H, V )â€¦ (More)

Bonin et al. (1993) recalled an open problem related to the recurrence relation verified by NSW numbers. The recurrence relation is the following: fn+l = 6f~ f~l , with jq = 1 and j~ = 7, and no combinatorial interpretation seems to be known. In this note, we define a regular language .~ whose number of words having length n is equal to f~+l. Then, by usingâ€¦ (More)

In this paper, we illustrate a bijective proof of the enumerative formula regarding non-separable rooted planar maps N S, by means of a class L of certain ternary trees (called left trees). Our rst step consists in determining the left trees' combinatorial enumeration according to the number of their internal nodes. We then establish a bijection between theâ€¦ (More)