tlpvs: A pvs-Based ltl Verification System. In this paper we present our pvs implementation of a linear temporal logic verification system. The system includes a set of theories defining a temporal logic, a number of proof rules for proving soundness and response properties, and strategies which aid in conducting the proofs. In addition to implementing a framework for existing rules, we have also derived new methods which are particularly useful in a deductive ltl system. A distributed rank rule for the verification of response properties in parameterized systems is presented, and a methodology is detailed for reducing compassion requirements to justice requirements (strong fairness to weak fairness). Special attention has been paid to the verification of unbounded systems – systems in which the number of processes is unbounded – and our verification rules are appropriate to such systems.