in online catalogs, searching based on subject keywords, comprise a significant percentage of searches. various studies, especially those of us origin, have stated it to be more than 50 percent. due to the importance of subject searching in online cataloging systems for users, much efforts is being exerted on the part of researchers and designers of such cataloging systems to increase its perfo...

We consider the problem of searching m branches which, with the exception of a common source s, are disjoint (hereafter called concurrent branches). A searcher, starting at s, must find a given “exit” t whose location, unknown to the searcher, is on one of the m branches. The problem is to find a strategy that minimizes the worst case ratio between the total distance traveled and the length of ...

The paper considers the exact number of character comparisons needed to nd all occurrences of a pattern of length m in a text of length n using on-line and general algorithms. For on-line algorithms, a lower bound of about (1 + 9 4(m+1)) n character comparisons is obtained. For general algorithms, a lower bound of about (1 + 2 m+3) n character comparisons is obtained. These lower bounds complem...

We describe a new method for decomposing planar sets of segments and points. Using this method we obtain new efficient deterministic algorithms for counting pairs of intersecting segments, and for answering off-line triangle rang'e queries. In particular we obtain the following results: (1) Given n segments in the plane, the number K of pairs of intersecting segments is computed in time O(nl+ f...