Abstract: In this paper, we present two new ranking and unranking
algorithms for k-ary trees represented by x-sequences in Gray
code order. These algorithms are based on a gray code generation algorithm
developed by Ahrabian et al.. In mentioned paper, a recursive
backtracking generation algorithm for x-sequences corresponding to
k-ary trees in Gray code was presented. This generation algorithm
is based on Vajnovszki-s algorithm for generating binary trees in
Gray code ordering. Up to our knowledge no ranking and unranking
algorithms were given for x-sequences in this ordering. we present
ranking and unranking algorithms with O(kn2) time complexity for
x-sequences in this Gray code ordering
Abstract: In this paper, we present a methodology for finding
authoritative researchers by analyzing academic Web sites. We show
a case study in which we concentrate on a set of Czech computer
science departments- Web sites. We analyze the relations between
them via hyperlinks and find the most important ones using several
common ranking algorithms. We then examine the contents of the
research papers present on these sites and determine the most
authoritative Czech authors.