Trapezoid graphs are the intersection family of trapezoids where every trapezoid has a pair of opposite sides lying on two parallel lines. These graphs have received considerable attention and lie strictly between permutation graphs (where the trapezoids are lines) and cocomparability graphs (the complement has a transitive orientation). The operation of “vertex splitting”, introduced in [3], f...

Actin stress fibers (SFs) of cells cultured on cyclically stretched substrate tend to reorient in the direction in which a normal strain of substrate becomes zero. However, little is known about the mechanism of this reorientation. Here we investigated the effects of cyclic stretch waveform on SF reorientation in osteoblastic cells. Cells adhering to silicone membranes were subjected to cyclic ...

Abstract A family of bivariate copulas given by: for v + 2 u < v+2u\lt 2 , C ( , ) = F − 1 ∕ C\left(u,v)=F\lef...

The paper answers the three distinct questions of maximizing the perimeter, diameter and area of equilateral unit-width convex polygons. The solution to each of these problems is trivially unbounded when the number of sides is even. We show that when this number is odd, the optimal solution to these three problems is identical, and arbitrarily close to a trapezoid. The paper also considers the ...

Hain’s trapezoidation algorithm is a fast, practical algorithm for the reduction of simple polygons into horizontally aligned trapezoids partitioned into a minimal collection of trapezoid sequences. An extension to this algorithm is described which allows trapezoidation of simple polygons with an arbitrary number of non-intersecting holes. The minimal computational cost per hole is a traversal ...

Given a simple graph G = (V, E) and a fixed positive integer k. In a graph G, a vertex is said to dominate itself and all of its neighbors. A set D ⊆ V is called a k-tuple dominating set if every vertex in V is dominated by at least k vertices of D. The k-tuple domination problem is to find a minimum cardinality k-tuple dominating set. This problem is NP-complete for general graphs. In this pap...

The intersection graph of a collection of trapezoids with corner points lying on two parallel lines is called a trapezoid graph. Using binary indexed tree data structure, we improve algorithms for calculating the size and the number of minimum vertex covers (or independent sets), as well as the total number of vertex covers, and reduce the time complexity from O(n) to O(n log n), where n is the...

In his 1998 paper, Ryan classified the sets of unit, proper, and plain trapezoid and parallelogram orders. We extend this classification to include unit, proper, and plain triangle orders. We prove that there are 20 combinations of these properties that give rise to distinct classes of ordered sets, and order these classes by containment. Mathematics Subject Classifications (2000) 06A06, 05C62