For each of the following strings, say whether it is a syntactically legal operation definition.
a. |
a(X) :: p(X,Y) ==> q(Y,X) |
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b. |
a(X) :: p(X,Y) & a(Y) ==> q(Y,X) |
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c. |
a(X) :: p(X,Y) ==> q(Y,X) & a(Y) |
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d. |
a(X) :: p(X,Y) ==> q(Y,X) & ~a(Y) |
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e. |
a(X) :: p(Y,Y) ==> q(X,Y) |
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