Fault-tolerant distributed algorithms play an important role in many critical/high-availability
applications. These algorithms are notoriously difficult to implement correctly, due to …

More than 30 years after their inception, the decidability proofs for reach ability in vector
addition systems (VAS) still retain much of their mystery. These proofs rely crucially on a …

Tree structures are used extensively in domains such as computational biology, pattern
recognition, XML databases, computer networks, and so on. In this paper, we present …

We consider the analysis of infinite half-duplex systems made of finite state machines that
communicate over unbounded channels. The half-duplex property for two machines and two …

We consider first-order logic over the subword ordering on finite words where each word is
available as a constant. Our first result is that the Σ 1 theory is undecidable (already over two …

Symbolic model checking provides partially effective verification procedures that can handle
systems with an infinite state space. So-called “acceleration techniques” enhance the …

We describe a simple, conceptual forward analysis procedure for infinity-complete WSTS S.
This computes the so-called clover of a state. When S is the completion of a WSTS X, the …

The problem of deciding the satisfiability of a quantifier-free formula with respect to a
background theory, also known as Satisfiability Modulo Theories (SMT), is gaining …

The downward closure of a word language is the set of all (not necessarily contiguous)
subwords of its members. It is well-known that the downward closure of any language is …

We study the complexity of the inclusion, equivalence, and intersection problem of extended
chain regular expressions (eCHAREs). These are regular expressions with a very simple …