We give the first efficient parallel algorithms for solving the arrangement problem. We give a deterministic algorithm for the CREW PRAM which runs in nearly optimal bounds of O(log n log∗ n) time and n2/ log n processors. We generalize this to obtain an O(log n log∗ n)-time algorithm using nd / log n processors for solving the problem in d dimensions. We also give a randomized algorithm for th...

We analyze how to efficiently maintain and update the visibility polygons for a segment observer moving in a polygonal domain. The space and time requirements for preprocessing are O(n) and after preprocessing, visibility change events for weak and strong visibility can be handled in O(log |VP|) and O(log(|VP1| + |VP2|)) respectively, or O(log n) in which |VP| is the size of the line segment’s ...

Let P be a planar n-point set. A k-partition of P is a subdivision of P into dn/ke parts of roughly equal size and a sequence of triangles such that each part is contained in a triangle. A line is k-shallow if it has at most k points of P below it. The crossing number of a k-partition is the maximum number of triangles in the partition that any k-shallow line intersects. We give a lower bound o...

There are several interesting observations to be made concerning the tape complexity of context-free languages. An early result given by Lewis et al. (1965) is that every context-free language can be recognized by an off-line deterministic Turing machine of O((log n) 2) tape complexity. This is still the best result known. Sudborough (1975) shows that if all linear context-free languages can be...

We present a new on-line algorithm for computing the Lempel-Ziv factorization of a string that runs in O(N logN) time and uses only O(N log σ) bits of working space, where N is the length of the string and σ is the size of the alphabet. This is a notable improvement compared to the performance of previous on-line algorithms using the same order of working space but running in either O(N log3 N)...

Detection of Oil-Water Contacts (OWCs) is one of the primary tasks before evaluation of reservoir’s hydrocarbon in place, determining net pay zones and suitable depths for perforation operation. This paper introduces Bayesian decision making tool as an effective technique in OWC detecting using wire line logs. To compare strengths of the suggested method in detecting OWC with conventional one, ...