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Last modified 10/20/2020 7:33:38 AM

Prove the robustness and functionality of critical units of the SPARK standard library

Paris, France
BAC +4/5

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Prove the robustness and functionality of critical units of the SPARK standard library


SPARK is a subset of the Ada programming language, together with formal verification tools which allow giving mathematical guarantees about SPARK programs, from correct data flows to absence of runtime errors to correct implementation of functional requirements. SPARK is open source and freely available to the Community on as well as professionally supported by AdaCore, which co-develops SPARK with Altran and Inria. 


The subject of this internship is to prove the correctness of critical parts of the SPARK standard library: primarily the units that manipulate characters and strings; then the runtime units that are used by the compiler to implement fixed-point arithmetic. The student will need to use the SPARK proof tools to demonstrate that no execution of these units can raise an exception (aka absence of runtime errors). The student will then add suitable contracts to these units that express the intended functionality as documented in the Ada Reference Manual, and use the SPARK proof tools to demonstrate that the implementation of the units respect these contracts. An initial source of inspiration for the expected results is the work done around “SPARK by Example” by a team at ISAE-SUPAERO (see More complex programs such as an implementation of algorithm D by Knuth for multi-place division will require advanced use of the proof tools, with ghost code and unbounded arithmetic (see e.g. a blog post presenting such techniques at


Skills required: The work will require good understanding of program semantics, as well as capabilities in proving properties over programs.

Timeframe and location: 

The internship will take place in the offices of AdaCore in Paris or Toulouse. 


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