用真值表的方法判定下面判断的逻辑关系(1)如果甲是罪犯,那么乙就不是罪犯。(2)甲是罪犯并且乙也是罪犯。解:用p表示“甲是罪犯”,用q表示“乙是罪犯”,则两个判断分别表示为p→﹁q和p∧q由真值表可知,两个判断为矛盾关系。题目中判断(2)的真值应为:
A. --++
B. ++--
C. -+++
D. +---
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用真值表的方法判定下列判断的关系(1)只有甲在现场,乙才在现场。(2)如果甲没在现场,乙也没在现场。解:用p表示“甲在现场”,用q表示“乙在现场”由真值表可知,两个判断为等值关系。题目中两个判断应分别表示为()
A. (1)p←q(2)﹁p→﹁q
B. (1)p←q(2)﹁p→q
C. (1)p←q(2)p→﹁q
D. (1)p→q(2)﹁p→﹁q
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