Causality & Control Flow

Robert Künnemann
(CISPA Helmholtz Center for Information Security)
Deepak Garg
(MPI-SWS)
Michael Backes
(CISPA Helmholtz Center for Information Security)

Causality has been the issue of philosophic debate since Hippocrates. It is used in formal verification and testing, e.g., to explain counterexamples or construct fault trees. Recent work defines actual causation in terms of Pearl's causality framework, but most definitions brought forward so far struggle with examples where one event preempts another one. A key point to capturing such examples in the context of programs or distributed systems is a sound treatment of control flow. We discuss how causal models should incorporate control flow and discover that much of what Pearl/Halpern's notion of contingencies tries to capture is captured better by an explicit modelling of the control flow in terms of structural equations and an arguably simpler definition. Inspired by causality notions in the security domain, we bring forward a definition of causality that takes these control-variables into account. This definition provides a clear picture of the interaction between control flow and causality and captures these notoriously difficult preemption examples without secondary concepts. We give convincing results on a benchmark of 34 examples from the literature.

In Georgiana Caltais and Jean Krivine: Proceedings of the 4th Workshop on Formal Reasoning about Causation, Responsibility, and Explanations in Science and Technology (CREST 2019), Prague, Czech Republic, 7th April 2019, Electronic Proceedings in Theoretical Computer Science 308, pp. 32–46.
Published: 31st October 2019.

ArXived at: http://dx.doi.org/10.4204/EPTCS.308.3 bibtex PDF
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