Select the most appropriate statement about each formula. 1: ∀x∀y (x = y → y = x) 2: ∀x (¬(x = x)) 3: ∀x∀y (R(x,y) → ¬R(y,x)) 4: ∃x ∀y R(x,y)匹配题

A

not true in any model

B

true in model with universe {a,b,c} and R = {(a,b), (a,c), (a, a)}

C

true in every model

D

true in model with universe {a,b,c} and R = {(a,b), (b,c), (c,a)}

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[math: ∀x(¬P(x)→Q(x))]

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