This paper presents a type theoretical framework for the verification of compiler optimizations. Although today's compiler optimizations are fairly advanced, there is still not an appropriate theoretical framework for the verification of compiler optimizations. To establish a generalized theoretical framework, we introduce assignment types for variables that represent how the value of variables will be calculated in a program. In this paper, first we introduce our type system. Second we prove soundness of our type system. This implies that the given two programs are equivalent if their return values are equal in types. Soundness ensures that many structure preserving optimizations preserve program semantics. Furthermore, by extending the notion of type equality to order relations, we redefine several optimizations and prove that they also preserve program semantics.
In this paper, we show an algorithm of LTL (linear temporal logic) model checking for LL-GG-TRS with regular tree valuation. The class LL-GG-TRS is defined as a subclass of term rewriting systems, and extends the class of pushdown systems (PDS) in the sence that pushdown stack of PDS is extended to tree structure. By this extension, we can model recursive programs with exception handling.
We formally verify the correctness of Transition System Reduction (TSR), an algorithm used in modelcheckers for temporal logics. Formalizing TSR as a function, we formulate and prove its correctness within the proof assistant PVS. We show how to use a well-ordering on a certain set in a termination proof for the loop-based TSR algorithm. We further detail TSR's partial-correctness proof. The formal framework for these proofs is a part of our research for a rigorous verification environment for reactive systems.
We present a DNA sequence analyzing system for a cellular slime mold called Dictyostelium discoideum. The upstream sequences may include cis-elements which are involved in the temporal and spatial regulation of transcription. Our goal is to identify the cis-elements with statistic methods. For this purpose, we have developed a distributed system. Its main components are an alignment program based on dynamic programming which estimates candidates for cis-elements on upstream sequences, and a statistical analyzer which checks if the candidate elements have a statistical property. The system supports SOAP and the components can be deployed and collaborate on the web. In this paper, we mainly discuss the system architecture and evaluate its efficiency.