| 1. |
- Abbasi, Rosa, et al.
(author)
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Combining rule- and SMT-based reasoning for verifying floating-point Java programs in KeY
- 2023
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In: International Journal on Software Tools for Technology Transfer. - : Springer Science and Business Media LLC. - 1433-2779 .- 1433-2787. ; 25:2, s. 185-204
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Journal article (peer-reviewed)abstract
- Deductive verification has been successful in verifying interesting properties of real-world programs. One notable gap is the limited support for floating-point reasoning. This is unfortunate, as floating-point arithmetic is particularly unintuitive to reason about due to rounding as well as the presence of the special values infinity and ‘Not a Number’ (NaN). In this article, we present the first floating-point support in a deductive verification tool for the Java programming language. Our support in the KeY verifier handles floating-point arithmetics, transcendental functions, and potentially rounding-type casts. We achieve this with a combination of delegation to external SMT solvers on the one hand, and KeY-internal, rule-based reasoning on the other hand, exploiting the complementary strengths of both worlds. We evaluate this integration on new benchmarks and show that this approach is powerful enough to prove the absence of floating-point special values—often a prerequisite for correct programs—as well as functional properties, for realistic benchmarks.
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| 2. |
- Abbasi, Rosa, et al.
(author)
-
Deductive Verification of Floating-Point Java Programs in KeY
- 2021
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In: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. ; 12652 LNCS, s. 242-261
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Conference paper (peer-reviewed)abstract
- Deductive verification has been successful in verifying interesting properties of real-world programs. One notable gap is the limited support for floating-point reasoning. This is unfortunate, as floating-point arithmetic is particularly unintuitive to reason about due to rounding as well as the presence of the special values infinity and ‘Not a Num-ber’ (NaN). In this paper, we present the first floating-point support in a deductive verification tool for the Java programming language. Our support in the KeY verifier handles arithmetic via floating-point decision procedures inside SMT solvers and transcendental functions via axiomatization. We evaluate this integration on new benchmarks, and show that this approach is powerful enough to prove the absence of floating-point special values—often a prerequisite for further reasoning about numerical computations—as well as certain functional properties for realistic benchmarks.
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| 3. |
- Schiffl, Jonas, et al.
(author)
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Formal Analysis of Smart Contracts: Applying the KeY System
- 2020
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In: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. ; , s. 204-218
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Book chapter (other academic/artistic)abstract
- Smart contracts are programs running on decentralized, distributed ledger platforms. Rigorous formal analysis of these programs is highly desirable because they manage valuable assets and therefore are a prime target for security attacks. In this paper, we show that the computation model of smart contracts allows the application of formal methods designed for analysing single-threaded imperative programs. We discuss different classes of correctness properties and the formal methods that may be applied. Furthermore, we show how deductive program verification in particular can be used to prove correctness of smart contracts, and we discuss two approaches where we have applied the program verification tool KeY.
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