On the Linear Ranking Problem for Simple Floating-Point Loops

Etienne Payet (1) , Fonenantsoa Maurica Andrianampoizinimaro (1) , Frédéric Mesnard (1)

1 LIM - Laboratoire d'Informatique et de Mathématiques

Termination of loops can be inferred from the existence of linear ranking functions. We already know that the existence of thesefunctions is PTIME decidable for simple rational loops. Since very recently, we know that the problem is coNP-complete for simple integer loops. We continue along this path by investigating programs dealing with floating-point computations. First, we show that the problem is at least in coNP for simple floating-point loops. Then, in order to work around that theoretical limitation we present an algorithm which remains polynomial by sacrificing completeness. The algorithm, based on the Podelski-Rybalchenko algorithm, can also synthesize in polynomial time the linear ranking functions it detects. To our knowledge, our work is the first adaptation of this well-known algorithm to floating-points.

Mots clés: Termination analysis; Linear ranking functions; Floating-point numbers

Domaines: Informatique [cs]

Etienne Payet, Fonenantsoa Maurica Andrianampoizinimaro, Frédéric Mesnard. On the Linear Ranking Problem for Simple Floating-Point Loops. 23rd International Symposium on Static Analysis (SAS), Sep 2016, Edinburgh, United Kingdom. pp.300-316, ⟨10.1007/978-3-662-53413-7_15⟩. ⟨hal-01451688⟩