A connected edge-colored graphG is said to be rainbow-connected if any two distinct vertices of G are connected by a path whose edges have pairwise distinct colors, and the rainbow connection number rc(G) ofG is the minimum number of colors that can make G rainbow-connected. We consider families F of connected graphs for which there is a constant kF such that every connected F-free graph G with...

Categorical skew lattices are a variety of skew lattices on which the natural partial order is especially well behaved. While most skew lattices of interest are categorical, not all are. They are characterized by a countable family of forbidden subalgebras. We also consider the subclass of strictly categorical skew lattices.

We characterize graphs that have intersection representations using unit intervals with open or closed ends such that all ends of the intervals are integral in terms of infinitely many minimal forbidden induced subgraphs. Furthermore, we provide a quadratic-time algorithm that decides if a given interval graph admits such an intersection representation.

An undirected graph G = (V, E) is a probe split graph if its vertex set can be partitioned into two sets, N (nonprobes) and P (probes) where N is independent and there exists E′ ⊆ N ×N such that G′ = (V, E ∪ E′) is a split graph. Recently Chang et al. gave an O(V (V +E)) time recognition algorithm for probe split graphs. In this article we give O(V 2 +V E) time recognition algorithms and charac...

A method for recognition of Persian handwritten digits based on characterization loci and mixture of experts is proposed. This method utilizes the characterization loci, as the main feature. In the classification stage of our proposed method the mixture of experts are applied. This recognition method is applied to Farsi hand-written digits in the HODA database. The experimental results support ...

Recently Postnikov gave a combinatorial description of the cells in a totallynonnegative Grassmannian. These cells correspond to a special class of matroids called positroids. We prove his conjecture that a positroid is exactly an intersection of permuted Schubert matroids. This leads to a combinatorial description of positroids that is easily computable. The main proof is purely combinatorial,...

Screening of3000 soil samples collected from cities of four different provinces of Iran for starch-hydrolysing bacteria revealed that the nature is enriched with Streptomyces species capable of producing amylolytic enzymes. Among the bacterial isolates, one of the high starch-degrading strains was selected for further microbiological identification and also amylolytic enzyme(s) characteriza...

Methylmalonic acidemia (MMA) is usually caused by a deficiency of the enzyme methylmalonyl-CoA mutase (MCM), a defect in the transport or synthesis of its cofactor, adenosyl-cobalamin (cblA, cblB, cblC, cblF, cblD, and cblX), or deficiency of the enzyme methylmalonyl-CoA epimerase. A comprehensive diagnostic approach involves investigations of metabolites with tandem mass spectrometry, organic ...

thirty-five fungal strains which isolated from vegetable wastes, were screened for the use of polygalacturonic acid as the sole carbon source. twenty-five isolates were positive for polygalacturonase activity in cup-plate assay, as evidenced by clear hydrolysation zones. the most productive strain was determined by measuring clear zones formed around colonies stained with ruthenium red. the hig...

methylmalonic acidemia (mma) is usually caused by a deficiency of the enzyme methylmalonyl-coa mutase (mcm), a defect in the transport or synthesis of its cofactor, adenosyl-cobalamin (cbla, cblb, cblc, cblf, cbld, and cblx), or deficiency of the enzyme methylmalonyl-coa epimerase. a comprehensive diagnostic approach involves investigations of metabolites with tandem mass spectrometry, organic ...