An SMT Approach to Bounded Reachability Analysis of Model Programs

Abstract. Model programs represent transition systems that are used to specify expected behavior of systems at a high level of abstraction. The main application area is application-level network protocols or protocol-data types such as sets and maps, and comprehensions to express com-plex state updates. Such models are mainly used in model-based testing as inputs for test case generation and as oracles during conformance testing. Correctness assumptions about the model itself are usually ex-pressed through state invariants. An important problem is to validate the model prior to its use in the above-mentioned contexts. We intro-duce a technique of using Satisfiability Modulo Theories or SMT to per-form bounded reachability analysis of a fragment of model programs. We use the Z3 solver for our implementation and benchmarks, and we use AsmL as the modeling language. The translation from a model program into a verification condition of Z3 is incremental and involves selective quantifier instantiation of quantifiers that result from the comprehension expressions.

Role of Ectonucleotidases in the Synapse Formation During Brain Development: Physiological and Pathological Implications

Extracellular adenine nucleotides and nucleosides, such as ATP and adenosine, are among the most recently identified and least investigated diffusible signaling factors that contribute to the structural and functional remodeling of the brain, both during embryonic and postnatal development. Their levels in the extracellular milieu are tightly controlled by various ectonucleotidases: ectonucleotide pyrophosphatase/phosphodiesterases (E-NPP), alkaline phosphatases (AP), ectonucleoside triphosphate diphosphohydrolases (E-NTPDases) and ecto-5'-nucleotidase (eN). During central nervous system development and in adulthood all ectonucleotidases have diverse expression pattern, cell specific localization and function. Formation, maturation, and refinement of synaptic contacts are influenced by neurotransmitters and neuromodulators, and control of extracellular adenine nucleotide levels by ectonucleotidases are important for understanding the role of purinergic signaling in developing tissues and potential targets in developmental disorders such as autism