spatial pattern of trees can possibly indicate stand history, population dynamics, and species competition. this research was investigated in the chahartagh forest reserve, ardal region, chaharmehal and bakhtiari province, central zagros forest, and southwest iranian state. in this study 53 hectare of the study area was selected and perfect inventory.  information includes the position and kind...

This paper considers the collusive stability of downstream competition in a vertical market with network externalities and cost asymmetry. A dynamic collusion game is constructed, backward induction employed to solve subgame perfect Nash equilibrium. We show that larger lead less incentive for an inefficient firm, while efficient this depends on efficiency gap. An increase will destabilize when...

Evolution of spin polarization in the presence external electric field is studied for collision energies $\sqrt{{s}_{\mathrm{NN}}}=27\text{ }\text{ }\mathrm{GeV}$ and $\sqrt{{s}_{\mathrm{NN}}}=200\text{ }\mathrm{GeV}$. The numerical analysis done perfect-fluid Bjorken-expanding resistive magnetohydrodynamic background novel results are reported. In particular, we show that plays a significant r...

The construction of joins and secant varieties is studied in the combinatorial context of monomial ideals. For ideals generated by quadratic monomials, the generators of the secant ideals are obstructions to graph colorings, and this leads to a commutative algebra version of the Strong Perfect Graph Theorem. Given any projective variety and any term order, we explore whether the initial ideal o...

Perfect graphs were defined by Claude Berge in the 1960s. They are important objects for graph theory, linear programming and combinatorial optimization. Claude Berge made a conjecture about them, that was proved by Chudnovsky, Robertson, Seymour and Thomas in 2002, and is now called the strong perfect graph theorem. This is a survey about perfect graphs, mostly focused on the strong perfect gr...

We develop a continuous-time dynamic model of competition with switching costs to show that in a relatively simple Markov Perfect equilibrium, the dominant …rm concedes market share by charging higher prices than the smaller …rm. In the short-run, switching costs might have two types of anti-competitive e¤ects: …rst, higher switching costs imply a slower transition to a symmetric market structu...