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Explain the structure of well formed formulae in relational calculus.
Ans: a. An atom is a formula
b. If P1 is a formula, after that so are ¬P1 and (P1)
c. If P1 and P2 are formulae, after that so are P1 V P2, P1 ^ P2, P1 → P2
d. If P1(s) is a formula containing a free variable s and r is a relation after that
∃ s ε r (P1(s) ) and ∀ s ε r (P1(s)) are also formulae
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