The vertex cover problem and the vertex partition problem are central problems in graph theory and many generalizations are known. Two examples are the minimum k-path vertex cover problem (MkPVCP for short, introduced in [1]), which asks for a minimum vertex sets covering every path of length k−1, and the minimum k-path partition problem (MkPPP for short, introduced in [2]), which asks for a mi...

Landsat remote sensing of the central African humid tropics is confounded by persistent cloud cover and, since 2003, missing data due to the Landsat-7 Enhanced Thematic Mapper Plus (ETM + ) scan line corrector (SLC) malfunction. To quantify these limitations and their effects on contemporary forest cover and change characterization, a comparison was made of multiple Landsat-7 image mosaics gene...

in this research، job opportunities have been examined among 26 productive sectors of iran's economy by using input-output table in 2001.from viewpoint of employment ،production and value added، the key sectors has been diagnosed by using mri ، elasticity of input-output table، backward and forward linkages and june's corrective methods. then، job opportunities has been analyzed among...

We present a non-perturbative solution of large N matrix models modified by terms of the form g(TrΦ4)2, which add microscopic wormholes to the random surface geometry. For g < gt the sum over surfaces is in the same universality class as the g = 0 theory, and the string susceptibility exponent is reproduced by the conventional Liouville interaction ∼ eα+φ. For g = gt we find a different univers...

There are many long-standing open problems on cubic bridgeless graphs, for instance, Jaeger’s directed cycle double cover conjecture. On the other hand, many structural properties of braces have been recently discovered. In this work, we bijectively map the cubic bridgeless graphs to braces which we call the hexagon graphs, and explore the structure of hexagon graphs. We show that hexagon graph...

The purpose of this paper is to establish an integral connection between the relative K-theory and cyclic homology of a square-zero ideal IeR, R a ring with unit. We restrict attention to the case when R is a split extension of R/I by I. The outline of the paper is as follows: in Section 2, we compute a direct summand of HC*(R, I), where HC*(R, 1) is graded in analogy to relative K-theory and f...

Bars in galaxies are mainly supported by particles trapped around closed periodic orbits. These orbits respond to the bar’s forcing frequency only and lack free oscillations. We show that a similar situation takes place in double bars: particles get trapped around orbits which only respond to the forcing from the two bars and lack free oscillations. We find that writing the successive positions...

In this paper we check the validity of the ideas of double scaling as given by Ball and Forte in a semi inclusive process like J/ψ production at HERA, in different kinematical regions, for low values of the Bjorken variable x. In particular, we study J/ψ production in the inelastic and diffractive (elastic) regimes using the double scaling form of the gluon distribution functions. We compare th...

The problem of comparison of the stationary axisymmetric vacuum solutions obtained within the framework of exact and approximate approaches for the description of the same general relativistic systems is considered. We suggest two ways of carrying out such comparison: (i) through the calculation of the Ernst complex potential associated with the approximate solution whose form on the symmetry a...

Jaeger’s directed cycle double cover conjecture can be formulated as a problem of existence of special perfect matchings in a class of graphs that we call hexagon graphs. In this work, we explore the structure of hexagon graphs. We show that hexagon graphs are braces that can be generated from the ladder on 8 vertices using two types of McCuaig’s augmentations.