Solving the Apprentice Challenge with 3VMC

Our solution of the apprentice challenge is based on [2] and does not assume any a priori bound on the number of Job threads or on the value of the counter field. This should be contrasted with previous attempts to solve the apprentice challenge using model-checking (i.e., the “finite Apprentice”). In our solution, we use the predicates of Table 1. The set Fields contains all fields used in the program. The set Labels contains all program labels. The predicates zero(v) and successor(v1, v2) are used to represent integer values as a sequence starting with a node v0 representing the value 0, for which zero(v0) is true, and proceeding with successive nodes related by the successor(v1, v2) predicate. The model used here could be easily extended to handle the overflow of integer variables (by introducing a special terminating node in the representation of the integers). For simplicity, we do not introduce such overflow and assume that execution does not go beyond some (unspecified) maximal integer.