Anaesthesia for Jehovah's Witnesses

Management of anaesthesia for Jehovah's witnesses.

Minimum Witnesses for Unsatisfiable 2CNFs

We consider the problem of finding the smallest proof of unsatisfiability of a 2CNF formula. In particular, we look at Resolution refutations and at minimum unsatisfiable subsets of the clauses of the CNF. We give a characterization of minimum tree-like Resolution refutations that explains why, to find them, it is not sufficient to find shortest paths in the implication graph of the CNF. The ch...

Small Proof Witnesses for LF

We instrument a higher-order logic programming search procedure to generate and check small proof witnesses for the Twelf system, an implementation of the logical framework LF. In particular, we extend and generalize ideas from Necula and Rahul [16] in two main ways: 1) We consider the full fragment of LF including dependent types and higher-order terms and 2) We study the use of caching of sub...

Tableaux and Witnesses for the -calculus

Symbolic temporal logic model checking is an automatic veriication method. One of its main features is that a counterexample can be constructed when a temporal formula does not hold for the model. Most model checkers so far have restricted the type of formulae that can be checked and for which counterexamples can be constructed to fair CTL formulae. This paper shows how counterexamples and witn...

Dynamic Witnesses for Static Type Errors

Static type errors are a common stumbling block for newcomers to typed functional languages. We present a dynamic approach to explaining type errors by generating counterexample witness inputs that illustrate how an ill-typed program goes wrong. First, given an ill-typed function, we symbolically execute the body to synthesize witness values that make the program go wrong. We prove that our pro...