Consider Gödel's equational calculus contained in all of them: it allows the substitution of variables by arbitrary numerals in one step, and arbitrarily complex terms can be replaced by their numerical values, again, in one step. In general, a human calculator cannot carry out such ...
The validity of the trace (both w.r.t. the applicability of the computation steps and the numerical correctness of the result) can be established o ine by a trusted checker. For tools used at design time, we argue that this approach has several advantages over proving the calculator correct...