作者jayfrog (宅可宅 非常宅)
看板Math
标题[代数] ring & ideal
时间Thu Jan 13 16:42:25 2011
1.
Let R be a ring such that x^2=x for all x belong R.
Show that R is commutative.
2.
Let R be a commutative ring. If Mis an ideal, abbreviate MM by M^2.
Let M_1, M_2 be two ideals such that M_1+M_2=R.
Show that M_1 ^2 + M_2 ^2 =R
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Logic is invincible because in order to combat logic
it is necessary to use logic.
（逻辑是不可战胜的，因为要反对逻辑还得使用逻辑。）
By Pierre Boutroux
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