Shigeki Hagihara

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We are developing a secure and certified e-mail system AnZenMail that provides an experimental testbed for our cutting-edge security enhancement technologies. In addition to a provably secure message transfer protocol, we have designed and implemented a server (MTU) and a client (MUA) in order that they could survive recent malicious attacks such as(More)
Despite a lot of advances in biology and genomics, it is still difficult to utilise such valuable knowledge and information to understand and analyse large biological systems due to high computational complexity. In this paper we propose a modular method with which from several small network analyses we analyse a large network by integrating them. This(More)
We developed a method for analysing gene regulatory networks in a purely qualitative fashion. Behaviours of networks are captured as transition systems using propositions for gene states (ON or OFF), and those related to threshold values for gene activation/inhibition. Possible behaviours of networks are specified by logical formulae in Linear Temporal(More)
Probabilistic Computation Tree Logic (PCTL) and Continuous Stochastic Logic (CSL) are often used to describe specifications of probabilistic properties for discrete time and continuous time, respectively. In PCTL and CSL, the possibility of executions satisfying some temporal properties can be quantitatively represented by the probabilistic extension of the(More)
Many fatal accidents of safety critical reactive systems have occurred in unexpected situations which had not been considered during the design and test phases of the systems. To prevent these accidents, reactive systems should be designed to respond appropriately to any requests of any timing from environments. Verifying this property at specification(More)
Verifying realizability in the specification phase is expected to reduce the development costs of safety-critical reactive systems. If a specification is not realizable, we must correct the specification. However, it is not always obvious what part of a specification should be modified. In this paper, we propose a method for obtaining the location of flaws.(More)