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On the correctness of specs. Given a function and its pre- and post-conditions and , we say that f is correct wrt . , iff How may the spec be wrong? may be incorrect, i.e., t here may be , with ( or ) and. What does this mean for calls to f?.
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On the correctness of specs • Given a function and its pre- and post-conditions and , we say that f is correct wrt. , iff • How may the spec be wrong? • may be incorrect, i.e., • there may be , with ( or )and
What does this mean for calls to f? • How to we go about invocations of ? • So, if we need to prove , and then the ‘wrong’ are ‘good enough’ • If, instead, (or ), then we cannot prove