Due to resource constraints, tracing production applications often results in incomplete data. Nevertheless, developers ideally want answers to queries about the program’s execution beyond data explicitly gathered. For example, a developer may ask whether a particular program statement executed during the run corresponding to a given failure report. In this work, we investigate the problem of determining whether each statement in a program executed, did not execute, or may have executed, given a set of (possibly-incomplete) observations. Using two distinct formalisms, we propose two solutions to this problem. The first formulation represents observations as regular languages, and computes intersections over these languages using finite-state acceptors. The second formulation encodes the problem as a set of Boolean constraints, and uses answer-set programming to solve the constraints.