In an edge modi cation problem one has to change the edge set of a given graph as little as possible so as to satisfy a certain property. We prove the NP-hardness of a variety of edge modi cation problems with respect to some well-studied classes of graphs. These include perfect, chordal, chain, comparability, split and asteroidal triple free. We show that some of these problems become polynomi...

Formal methods have been traditionally used to model and verify operating systems Dif ferent methods verify di erent operating systems properties such as process management mutual exclusion and inter process communication Moreover various methods may capture di erent design errors such as deadlocks or unspeci ed receptions The system kernel supports higher level system services Hence kernel ver...

We describe a methodology for the speciication and veriication of the tasks of compiler fron-tends. The semantics of the language to be compiled is speciied with Evolving Algebras. With respect to the semantics of the language we deene the static semantics. The semantical analysis checks whether a program satisses the static semantics. We introduce a notion of correctness of semantic analysis a...

Zeolite encapsulated Co(II), Cu(II) and Zn(II) complexes with 2-methyl benzimidazole (Mebzlh) have been used to catalyze the reaction of styrene oxide with acetone under reflux condition. The yield of the isolated product using various catalysts range from good to excellent and the efficiency of the recycled catalyst was excellent.

Currently, many are investigating promising veriication methods based on Boolean decision diagrams (BDDs). Using BDDs, however, requires modeling the system under veriication in terms of Boolean formulas. This modeling can be diicult and error-prone, especially when dealing with constructs like arithmetic, sequential control ow, and complex data structures. We present new techniques for automat...

We present a state-of-the-art computational study of the uranyl(vi) and uranyl(v) cation-cation interactions (dications) in aqueous solution. Reliable electronic structures of two interacting uranyl(vi) and uranyl(v) subunits as well as those of the uranyl(vi) and uranyl(v) clusters are presented for the first time. Our theoretical study elucidates the impact of cation-cation interactions on ch...

This paper is concerned with stochastic demand systems that arise from structural random utility models for J continuous choice variables. It examines under which conditions on the structural preference speci ̄cation the implied reduced form model is invertible. And it investigates the conditions under which the structural model can be locally identi ̄ed from the reduced form under moment assumpt...