Semialgebraic invariant synthesis for the Kannan-Lipton Orbit Problem

The Orbit Problem consists of determining, given a linear transformation A on Qd , together with vectors x and y, whether the orbit of x under repeated applications of A can ever reach y. This problem was famously shown to be decidable by Kannan and Lipton in the 1980s. In this paper, we are concern...

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Main Authors: Fijalkow, N, Ohlmann, P, Ouaknine, J, Pouly, A, Worrell, J
Format: Conference item
Published: Schloss Dagstuhl 2017
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author Fijalkow, N
Ohlmann, P
Ouaknine, J
Pouly, A
Worrell, J
author_facet Fijalkow, N
Ohlmann, P
Ouaknine, J
Pouly, A
Worrell, J
author_sort Fijalkow, N
collection OXFORD
description The Orbit Problem consists of determining, given a linear transformation A on Qd , together with vectors x and y, whether the orbit of x under repeated applications of A can ever reach y. This problem was famously shown to be decidable by Kannan and Lipton in the 1980s. In this paper, we are concerned with the problem of synthesising suitable invariants P ⊆ R d , i.e., sets that are stable under A and contain x and not y, thereby providing compact and versatile certificates of non-reachability. We show that whether a given instance of the Orbit Problem admits a semialgebraic invariant is decidable, and moreover in positive instances we provide an algorithm to synthesise suitable invariants of polynomial size. It is worth noting that the existence of semilinear invariants, on the other hand, is (to the best of our knowledge) not known to be decidable.
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spelling oxford-uuid:1f0cfb5a-f0d9-4858-9d63-8878effe024a2022-03-26T11:19:43ZSemialgebraic invariant synthesis for the Kannan-Lipton Orbit ProblemConference itemhttp://purl.org/coar/resource_type/c_5794uuid:1f0cfb5a-f0d9-4858-9d63-8878effe024aSymplectic Elements at OxfordSchloss Dagstuhl2017Fijalkow, NOhlmann, POuaknine, JPouly, AWorrell, JThe Orbit Problem consists of determining, given a linear transformation A on Qd , together with vectors x and y, whether the orbit of x under repeated applications of A can ever reach y. This problem was famously shown to be decidable by Kannan and Lipton in the 1980s. In this paper, we are concerned with the problem of synthesising suitable invariants P ⊆ R d , i.e., sets that are stable under A and contain x and not y, thereby providing compact and versatile certificates of non-reachability. We show that whether a given instance of the Orbit Problem admits a semialgebraic invariant is decidable, and moreover in positive instances we provide an algorithm to synthesise suitable invariants of polynomial size. It is worth noting that the existence of semilinear invariants, on the other hand, is (to the best of our knowledge) not known to be decidable.
spellingShingle Fijalkow, N
Ohlmann, P
Ouaknine, J
Pouly, A
Worrell, J
Semialgebraic invariant synthesis for the Kannan-Lipton Orbit Problem
title Semialgebraic invariant synthesis for the Kannan-Lipton Orbit Problem
title_full Semialgebraic invariant synthesis for the Kannan-Lipton Orbit Problem
title_fullStr Semialgebraic invariant synthesis for the Kannan-Lipton Orbit Problem
title_full_unstemmed Semialgebraic invariant synthesis for the Kannan-Lipton Orbit Problem
title_short Semialgebraic invariant synthesis for the Kannan-Lipton Orbit Problem
title_sort semialgebraic invariant synthesis for the kannan lipton orbit problem
work_keys_str_mv AT fijalkown semialgebraicinvariantsynthesisforthekannanliptonorbitproblem
AT ohlmannp semialgebraicinvariantsynthesisforthekannanliptonorbitproblem
AT ouakninej semialgebraicinvariantsynthesisforthekannanliptonorbitproblem
AT poulya semialgebraicinvariantsynthesisforthekannanliptonorbitproblem
AT worrellj semialgebraicinvariantsynthesisforthekannanliptonorbitproblem