From: Chantal Ykman (

ASSASSIN is the IMEC compiler for synthesis and analysis of asynchronous control circuits. It is an evolving system being developed by Peter Vanbekbergen, Chantal Ykman, and Bill Lin. The software is written in "C" and should be portable to most workstation platforms.

The specification formalism used is a general "Timed" Signal Transition Graph (STG) Model. This model extends Chu's Signal Transition Graph model in a number of important ways. These extensions were required to specify and synthesize a wide class of industrial applications. For example, new types of events and Boolean guards have been introduced to permit the specification of mixed mode asynchronous/synchronous behavior. In addition, general Petri nets with complex conditional behaviors are permitted in our model, which is necessary to capture arbitration protocols. Also, timing semantics have been defined to model environmental requirements and assumptions. Other models, such as timing diagrams, may be translated to the timed STG model.

For the timed STG model, a number of algorithms have been developed to synthesize realistic design problems automatically. Some work at the STG level while others work on a state graph (SG) model. At the STG level, methods have been developed that can be used to synthesize and optimize circuits directly from the STG without first generating a state graph, where state explosion may occur. These methods enables synthesis of highly concurrent specifications, coming up with solutions where concurrency can be reduced in place of introducing unnecessary state signals, as well as taking into account complex timing constraints. At the state graph level, methods have been developed for exploring a large solution space where concurrency can be reduced and where new state signal transitions may be added in a concurrent way. These methods have the important advantage that they can be applied to a very large class of extended STG's, even non-STG formalisms as long as an initial state graph consistent with interleaved semantics can be derived.

We have a set of available papers and reports.

ASSASSIN is available for experimental non-commercial use free-of-charge. Currently it can be obtained via anonymous ftp to:

This directory contains "assassin2.0.tar.gz" and the README file, which also explains:

Contact : Bill Lin (, Chantal Ykman (