Abstracted Model Verification for Complex State Systems
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Solution Overview
Problem
The verification of complex hardware or software systems is challenging due to their exponentially large state spaces, making it computationally intractable to determine whether all reachable states are safe, especially with current bounded reachability methods that are incomplete and unable to find deep bugs.
Innovation Solution
A method is introduced that generates an abstracted model of the system by approximating data, operations, and predicates with uninterpreted terms, allowing for reachability analysis to determine if the system can reach unallowable states, with subsequent refinement of the model to eliminate infeasible steps and verification using the concrete model to distinguish real errors from abstraction errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bounded reachability analysis is performed on the concrete system model, then the analysis is computationally feasible, but the verification is incomplete and cannot find deep bugs
Solution Approach 1:
The patent introduces an abstracted model as an intermediary between the concrete system model and the verification process. This abstracted model uses uninterpreted terms and functions to represent data and operations, creating a simplified intermediate representation that enables complete reachability analysis while remaining computationally tractable. The abstraction layer acts as a mediator that preserves verification soundness while reducing complexity.
Solution Approach 2:
The patent creates an abstracted copy of the concrete system model. This copy maintains the essential structural and behavioral properties needed for verification while replacing concrete data representations with uninterpreted terms. The abstracted model is a simplified replica that enables exhaustive analysis without the computational burden of the full concrete state space.
2Reliability
If exact reachability analysis is performed on the full system, then complete verification is achieved, but the computation becomes intractable for complex systems
Solution Approach 1:
The patent extracts the essential verification-relevant properties from the concrete system model while leaving out unnecessary implementation details. By extracting only the critical control logic and state transitions into the abstracted model, the method enables complete reachability analysis on a simplified representation, avoiding the intractable computation of analyzing the full concrete system.
Solution Approach 2:
The patent changes the parameter representation in the model by replacing concrete data values and operations with uninterpreted terms and functions. This parameter transformation reduces the complexity of the state space while preserving the verification properties, enabling complete analysis in reasonable time.
3Measurement precision
If the abstracted model is refined to eliminate false errors, then the verification accuracy improves, but the refinement process increases computational complexity
Solution Approach 1:
The patent implements a feedback mechanism where the reachability analysis results on the abstracted model guide the refinement process. When false errors are detected, the method uses feedback from the unabstracted trace analysis to identify which abstractions need refinement, systematically improving the model's accuracy while managing complexity through targeted refinement rather than comprehensive reanalysis.
Data Source
AI summary
A method including the steps of: generating a system model, the model comprising an initial state, a transition between consecutive states and a property function defining a property that should be met for an allowable state, the initial state, transition function and property function each comprising at least one of data, operations and predicates; generating an abstracted model by approximating at least some of the data, operations and predicates with uninterpreted terms, functions and predicates respectively, to generate at least one abstracted initial state, abstracted transition function and abstracted property function within the abstracted model; performing a complete reachability analysis on the abstracted model to determine whether the system can reach an unallowable abstracted state by following the abstracted transition function; and if not, the system is verified as correct; and if so, unabstracting a trace of the transitions from the abstracted initial state to the unallowable abstracted state.