In the past， people used to make clothes and do repairs on things in the house more than nowadays. I think the difference between then and now has been___1___by a number of reasons such as the quantity of other___2___， the differe

義了新的環(huán)類，即中心弱Armendariz環(huán)，通過例子說明中心弱Armendariz環(huán)是弱Armendariz環(huán)的真推廣,也是中心Armendariz環(huán)的真推廣.因此，對中心弱Armendariz環(huán)的研究是有意義的.作者主要給出了中心弱Armendariz環(huán)的等價刻畫;說明了中心弱Armendariz環(huán)與Abelian環(huán)以及p.p.-環(huán)的關系；證明了若R是半素環(huán)且R[x]/(x2)是中心弱Armendariz，則R是約化環(huán)；若R/I是中心弱Armendar