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1、逻辑式与真值表,1.逻辑式概念,1、逻辑式,真值表概念,如何列真值表,一、分析式子中的逻辑变量及其个数,二、利用树形图分析列表的行数,三、根据式子分析列表列数,用真值表验证下列等式是否成立:,A,0,1,0,0,A,0,1,0,1,A,0,1,0,1,A,0,1,1,1,A,0,1,0,1,A,0,1,0,1,A,0,0,1,1,0,0,A,0,0,1,1,1,1,用真值表验证下列等式是否成立:,B,A,0,0,0,0,1,1,1,1,0,0,1,1,0,0,0,0,用真值表验证下列等式是否成立:,B,A,0,0,0,0,1,1,1,1,0,1,1,1,1,0,1,1,用真值表验证下列等式是否
2、成立:,A,B,C,A,B,C,0,0,0,0,1,1,1,1,0,0,0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0,1,1,1,1,1,1,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,0,0,0,0,0,1,1,1,用真值表验证下列等式是否成立:,A,B,C,A,B,C,0,0,0,0,1,1,1,1,0,0,0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,1,1,0,0,0,0,0,0,0,0,1,1,1,1,1,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,1,1,1,1,1,
3、用真值表验证下列等式是否成立:,用真值表验证下列等式是否成立:,B,A,0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,用真值表验证下列等式是否成立:,A,B,A,B,A,B,0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0,1,例2 完成下面的真值表,1,1,0,1,1,0,0,0,AB,A+B,B,A,1,0,1,0,1,0,1,1,0,0,0,1,0,0,1,B,A,B,A,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0,1,1,1,1,1,0,0,0,用真值表验证下列等式是否成立:,的值都相同,所以,三、例题与练习,三、例题与练习,等值逻辑式,例4如图所示,开关电路中的灯D的状态,能否用,开关A,B,C的逻辑运算来表示?试给出结果,分析这个电路,是开关A,B,C相并,联的电路,三个开关,中至少有一个“合上”,时,电灯D就亮所以使用逻辑加法,解D=A+B+C,三、例题与练习,A,B,三、例题与练习,练习2 填写下列真值表,AB,B,A,三、例题与练习,练习2 填写下列真值表,用真值表验证等式,用真值表验证等式,三、例题与练习,练习3,