Theorem-proving Verification of Multi-clock Synchronous Circuits on Multimoda...Shunji Nishimura
Formal verification methods for synchronous circuits are widely used, but almost all of the methods are limited to single-clock synchronous circuits. In this paper, we propose a formal verification method for multi-clock synchronous circuits. The proposed verification method is in theorem-proving manner and based on multimodal logic. We also show an example of verification of a clock switching circuit by using the method.
Approximate-At-Most-k Encoding of SAT for Soft ConstraintsShunji Nishimura
This document proposes an approximate encoding method for at-most-k constraints that reduces boolean expressions compared to conventional encodings, though it does not cover all possible solutions. It recursively applies at-most constraints by multiplying the number of variables. For a 2x2 recursive model, it achieves a 44% solution coverage using only 15% of the literals required by a sequential counter encoding. The approximate encoding is intended for use with soft constraints to efficiently search for better solutions, rather than finding all possible solutions.
Classification of Sequential Circuits as Causal FunctionsShunji Nishimura
This document proposes a new behavioral classification of sequential circuits that categorizes synchronous circuits and multi-clock domain circuits in the same class. The classification is based on whether the circuit's behavior is time-preserving, meaning the temporal progress of inputs results in the inclusion of output sets, or not time-preserving. This unifies the treatment of synchronous circuits and multi-clock domain circuits while capturing their behavioral differences from asynchronous circuits. Formal expressions and concepts like dependent types and domain restriction are discussed in applying this classification approach.
Typing during Lectures as an Alternative for Blackboard WritingShunji Nishimura
Blackboard writing is one of the most basic method to give a lecture for a long time, but these days, the necessity of handwriting is decreasing due to the widespread use of digital devices. This study proposes an alternative method for writing blackboards: to input contents through PC keyboards and show them on a projector screen.
Broad-sense Synchronous Circuits on Partially Ordered TimeShunji Nishimura
This document proposes a new definition of "broad-sense synchronous circuits" that generalizes conventional definitions. Broad-sense synchronous circuits are defined as those with an order-preserving referential map, which determines the time points a circuit can refer to in its feedback. This definition includes traditionally synchronous circuits using flip-flops but does not require them, and excludes memory-equipped circuits that can refer to arbitrary past times. The proposed definition aims to locate an appropriate level of generality between existing too-narrow and too-broad definitions of synchronous circuits.
Theorem-proving Verification of Multi-clock Synchronous Circuits on Multimoda...Shunji Nishimura
Formal verification methods for synchronous circuits are widely used, but almost all of the methods are limited to single-clock synchronous circuits. In this paper, we propose a formal verification method for multi-clock synchronous circuits. The proposed verification method is in theorem-proving manner and based on multimodal logic. We also show an example of verification of a clock switching circuit by using the method.
Approximate-At-Most-k Encoding of SAT for Soft ConstraintsShunji Nishimura
This document proposes an approximate encoding method for at-most-k constraints that reduces boolean expressions compared to conventional encodings, though it does not cover all possible solutions. It recursively applies at-most constraints by multiplying the number of variables. For a 2x2 recursive model, it achieves a 44% solution coverage using only 15% of the literals required by a sequential counter encoding. The approximate encoding is intended for use with soft constraints to efficiently search for better solutions, rather than finding all possible solutions.
Classification of Sequential Circuits as Causal FunctionsShunji Nishimura
This document proposes a new behavioral classification of sequential circuits that categorizes synchronous circuits and multi-clock domain circuits in the same class. The classification is based on whether the circuit's behavior is time-preserving, meaning the temporal progress of inputs results in the inclusion of output sets, or not time-preserving. This unifies the treatment of synchronous circuits and multi-clock domain circuits while capturing their behavioral differences from asynchronous circuits. Formal expressions and concepts like dependent types and domain restriction are discussed in applying this classification approach.
Typing during Lectures as an Alternative for Blackboard WritingShunji Nishimura
Blackboard writing is one of the most basic method to give a lecture for a long time, but these days, the necessity of handwriting is decreasing due to the widespread use of digital devices. This study proposes an alternative method for writing blackboards: to input contents through PC keyboards and show them on a projector screen.
Broad-sense Synchronous Circuits on Partially Ordered TimeShunji Nishimura
This document proposes a new definition of "broad-sense synchronous circuits" that generalizes conventional definitions. Broad-sense synchronous circuits are defined as those with an order-preserving referential map, which determines the time points a circuit can refer to in its feedback. This definition includes traditionally synchronous circuits using flip-flops but does not require them, and excludes memory-equipped circuits that can refer to arbitrary past times. The proposed definition aims to locate an appropriate level of generality between existing too-narrow and too-broad definitions of synchronous circuits.
Generalized Isomorphism between Synchronous Circuits and State MachinesShunji Nishimura
1) The document presents a generalized theory that models synchronous circuits and state machines using category theory.
2) It defines an evaluation operator and comprehensive latches to model circuits containing latches and flip-flops.
3) A natural transformation is used to transform the time structure of a circuit, showing an isomorphism between a D-latch circuit and corresponding state machine.
Generalized Isomorphism between Synchronous Circuits and State MachinesShunji Nishimura
1) The document presents a generalized theory that models synchronous circuits and state machines using category theory.
2) It defines an evaluation operator and comprehensive latches to model circuits containing latches and flip-flops.
3) A natural transformation is used to transform the time structure of a circuit, showing an isomorphism between a D-latch circuit and corresponding state machine.