Reconstructing discrete bidimensional sets from their projections is involved in many different problems of computer-aided tomography, pattern recognition, image processing and data compression. Inâ€¦ (More)

In a previous report, we studied the problem of reconKubaâ€™s heuristic algorithm [7] reconstructs some convex sets. structing a discrete set S from its horizontal and vertical projections. Some of theâ€¦ (More)

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 theâ€¦ (More)

A permutation avoids the subpattern i3 has no subsequence having all the same pairwise comparisons as , and we write âˆˆ S( ). We examine the classes of permutations, S(321); S(321; 37 142) and S(4231;â€¦ (More)

For every integer jÂ¿1, we de ne a class of permutations in terms of certain forbidden subsequences. For j = 1, the corresponding permutations are counted by the Motzkin numbers, and for j =âˆž (de nedâ€¦ (More)

A permutation is said to be â€“avoiding if it does not contain any subsequence having all the same pairwise comparisons as . This paper concerns the characterization and enumeration of permutationsâ€¦ (More)