Bidirection ≡ Ex-Nor ≡ iff ≡ Equivalence operator ≡ <=>
p<=>q means (p=>q )AND(q>p) which means (p'+q).(q'+p) which means p'q'+pq
Now the prepositional logic p'q'+pq would be true when either both p,q are false or both are true.so this make p,q logically equivalent iff p'q'+pq is true always.
like for example let p=a+b' and q= (a'b)' so as you can guess p is logically equivalent to q here
but you can prove it by using p<=>q if the outcome for all possible inputs is always true then p and q would be logically equivalent.
I think this condition is for bi-conditional statement not for logical equivalence.
i'm really not getting , what are you not getting. please tell me more clearly.
i am trying one more time.
If for same input p and q are generating different then their bidirectional formula (p<=>q) would generate output F that's simply mean p and q are not logically equivalent.
Compound prepositions p and q are called logically equivalent if p<=>q is a tautology.