which cannot be proved within the system . The need for these well-foundedness arguments is what gives rise to the author 's notion that there is "room for `proving' the complex fixpoint properties . " However, as the author himself remarks, neither is the construction of a tableau entirely algorithmi c and so it is hard to see what are "the checkable components of a property." Indeed, the complet e lack of indication which parts of the proof method are envisioned to be automated raises doubt s about the second half of the claim that "The book will be of particular interest to those concerne d with formal verification of systems, both in theory and in practice ." Chapter 4 presents a terse introduction to Petri nets, from which then some verification example s are drawn. Both safety and liveness properties of nets are proved . One section shows how net s with a replicative structure can be verified using schematic tableau proofs . Chapter 5 answer s some questions about the expressiveness of the mu-calculus on Petri nets and the complexity o f the local model checking problem . In particular, through an interesting connection with partially
/lp/association-for-computing-machinery/book-review-semantics-of-programming-languages-structures-and-LETLcDIGl5