【单选题】
谓词公式 ( x)(P(x)∨( y)R(y))→Q(x) 中变元x是___。
A. 自由变量
B. 约束变量
C. 既不是自由变量也不是约束变量
D. 既是自由变量也是约束变量
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答案
D
解析
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A. ﹁( x)( C(x) ﹁G(x) )
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【单选题】
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【单选题】
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【单选题】
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【单选题】
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