abstract in order to evaluation the effects of price policies (wheat guarantee price in each period and its price lag), environmental (planted area) and climatic (min and max average temperature, total annual precipitation, cold-day degree and hot-day degree) factors, we considered wheat yield in razavi-khorasan province (9 cities) for a 13-year statistical period (1371-72 to 1383-84). in this ...

Abstract This paper is concerned with description of the existence and forms entire solutions several second-order partial differential-difference equations more general Fermat type. By utilizing Nevanlinna theory meromorphic functions in complex variables we obtain some results on for these equations, which are extensions generalizations previous theorems given by Xu Cao (Mediterr. J. Math. 15...

Following an influential article by Angrist and Krueger (1992) on two-sample instrumental variables (TSIV) estimation, numerous empirical researchers have applied a computationally convenient two-sample two-stage least squares (TS2SLS) variant of Angrist and Krueger’s estimator. In the two-sample context, unlike the single-sample situation, the IV and 2SLS estimators are numerically distinct. W...

Hölder estimates for spatial second derivatives are proved for solutions of fully nonlinear parabolic equations in two space variables. Related techniques extend the regularity theory for fully nonlinear parabolic equations in higher dimensions.

This paper is a survey and systematic presentation of decidability and complexity issues for modal and non-modal two-variable logics. A classical result due to Mortimer says that the two-variable fragment of rst-order logic, denoted FO 2 , has the nite model property and is therefore decidable for satissability. One of the reasons for the signiicance of this result is that many propositional mo...