Automatic program verification in Dynamic Logic with applications to smart contracts

In critical systems, failures or errors can cause catastrophes, such as deaths or considerably losses of money. Model checking provides an automated way to prove the correctness of programs' requirements. It is a convenient technique to use in systems that need reliability. Propositional Dynamic Logic (PDL) is a formal system designed to reason about programs. This work presents a compiler implementation from a subset of the C language and also for the Smacco model, both to the PDL language, and after that to the language of the nuXmv model checker. This implementation is linked with a Blockchain model generation system to model and reason about smart contracts.

Symbiotic 8: Beyond Symbolic Execution

Symbiotic 8 extends the traditional combination of static analyses, instrumentation, program slicing, and symbolic execution with one substantial novelty, namely a technique mixing symbolic execution with k-induction. This technique can prove the correctness of programs with possibly unbounded loops, which cannot be done by classic symbolic execution.Symbiotic 8 delivers also several other improvements. In particular, we have modified our fork of the symbolic executorKleeto support the comparison of symbolic pointers. Further, we have tuned the shape analysis toolPredator(integrated already inSymbiotic 7) to perform better onllvmbitcode. We have also developed a light-weight analysis of relations between variables that can prove the absence of out-of-bound accesses to arrays.

Verifying Tight Logic Programs with anthem and vampire

This paper continues the line of research aimed at investigating the relationship between logic programs and first-order theories. We extend the definition of program completion to programs with input and output in a subset of the input language of the ASP grounder gringo, study the relationship between stable models and completion in this context, and describe preliminary experiments with the use of two software tools, anthem and vampire, for verifying the correctness of programs with input and output. Proofs of theorems are based on a lemma that relates the semantics of programs studied in this paper to stable models of first-order formulas.

Connecting Higher-Order Separation Logic to a First-Order Outside World

Separation logic is a useful tool for proving the correctness of programs that manipulate memory, especially when the model of memory includes higher-order state: Step-indexing, predicates in the heap, and higher-order ghost state have been used to reason about function pointers, data structure invariants, and complex concurrency patterns. On the other hand, the behavior of system features (e.g., operating systems) and the external world (e.g., communication between components) is usually specified using first-order formalisms. In principle, the soundness theorem of a separation logic is its interface with first-order theorems, but the soundness theorem may implicitly make assumptions about how other components are specified, limiting its use. In this paper, we show how to extend the higher-order separation logic of the Verified Software Toolchain to interface with a first-order verified operating system, in this case CertiKOS, that mediates its interaction with the outside world. The resulting system allows us to prove the correctness of C programs in separation logic based on the semantics of system calls implemented in CertiKOS. It also demonstrates that the combination of interaction trees + CompCert memories serves well as a lingua franca to interface and compose two quite different styles of program verification.

A New Approach to the Solution of the Fredholm Integral Equation via a Fixed Point on Extended b-Metric Spaces

It is very well known that real-life applications of fixed point theory are restricted with the transformation of the problem in the form of f ( x ) = x . (1) The Knaster–Tarski fixed point theorem underlies various approaches of checking the correctness of programs. (2) The Brouwer fixed point theorem is used to prove the existence of Nash equilibria in games. (3) Dlala et al. proposed a solution for magnetic field problems via the fixed point approach.

Utilizing Hoare Logic to Strengthen Testing for Error Detection in Programs

Hoare logic (also known as Floyd-Hoare logic) can be used to formally verify the correctness of programs while testing provides a practical way to detect errors in programs. Unfortunately, the former is rarely applied in practice and the later is difficult to detect all existing errors. In this paper, we propose a novel technique that makes good use of Hoare logic to strengthen testing. The essential idea is first to use specification-based testing to discover all traversed program paths and then to use Hoare logic to prove their correctness. During the proof process, all errors on the paths can be detected. A case study is conducted to show its feasibility; an example taken from the case study is used to illustrate how the proposed method is applied; and discussion on the potential challenges to the method is presented.

Review of Software Fault-Tolerance Methods for Reliability Enhancement of Real-Time Software Systems

Real time systems are those systems which must guarantee to response correctly within strict time constraint or within deadline. Failures can arise from both functional errors as well as timing bugs. Hence, it is necessary to provide temporal correctness of programs used in real time applications in addition to providing functional correctness. Although, there are several researches concerned with achieving fault tolerance in the presence of various functional and operational errors but many of them did not address the problem concerned with the timing bugs which is an important issue in real time systems. As for real time systems, many times it becomes a necessity for a given service to be delivered within the specified time deadline. Therefore, this paper reviews the existing approaches from the perspective of real time systems to analyse the shortcomings of these approaches to present a versatile and cost effective approach in the presence of timing bugs for providing fault tolerance to enhance the reliability of the real time software applications.

Review of Software Fault-Tolerance Methods for Reliability Enhancement of Real-Time Software Systems

Real time systems are those systems which must guarantee to response correctly within strict time constraint or within deadline. Failures can arise from both functional errors as well as timing bugs. Hence, it is necessary to provide temporal correctness of programs used in real time applications in addition to providing functional correctness. Although, there are several researches concerned with achieving fault tolerance in the presence of various functional and operational errors but many of them did not address the problem concerned with the timing bugs which is an important issue in real time systems. As for real time systems, many times it becomes a necessity for a given service to be delivered within the specified time deadline. Therefore, this paper reviews the existing approaches from the perspective of real time systems to analyse the shortcomings of these approaches to present a versatile and cost effective approach in the presence of timing bugs for providing fault tolerance to enhance the reliability of the real time software applications.