Loop Variant - Rule of Inference For Total Correctness

Rule of Inference For Total Correctness

In order to formally state the rule of inference for the termination of a while loop we have demonstrated above, recall that in Floyd–Hoare logic, the rule for expressing the partial correctness of a while loop is:

where I is the invariant, C is the condition, and S is the body of the loop. To express total correctness, we write instead:

\frac{< \textrm{\ is\ well-founded},\;\;S\;} {\;\mathbf{while}\;C\; \mathbf{do}\; S \;},

where, in addition, V is the variant, and by convention the unbound symbol z is taken to be universally quantified.

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