in this paper, we introduce a new generalization of weakly prime ideals called $i$-prime. suppose $r$ is a commutative ring with identity and $i$ a fixed ideal of $r$. a proper ideal $p$ of $r$ is $i$-prime if for $a, b in r$ with $ab in p-ip$ implies either $a in p$ or $b in p$. we give some characterizations of $i$-prime ideals and study some of its properties.  moreover, we give conditions  ...

selection of best demand model for explaining of consumer behaviour is one of the most important issues in microeconomic. in this paper we introduce aids[1],cbs[2], nbr[3] and rotterdam model and estimate these models by iranian urban households data for period 1973-2012.seemingly unrelated regression method is chosen for estimation of 5 groups of commodities including food, housing, clothing, ...