Sequential relational decomposition

The concept of decomposition in computer science and engineering is considered a fundamental component of computational thinking and is prevalent in design of algorithms, software construction, hardware design, and more. We propose a simple and natural formalization of sequential decomposition, in w...

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Main Authors: Fried, D, Legay, A, Ouaknine, J, Vardi, M
Format: Conference item
Published: Association for Computing Machinery 2018
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author Fried, D
Legay, A
Ouaknine, J
Vardi, M
author_facet Fried, D
Legay, A
Ouaknine, J
Vardi, M
author_sort Fried, D
collection OXFORD
description The concept of decomposition in computer science and engineering is considered a fundamental component of computational thinking and is prevalent in design of algorithms, software construction, hardware design, and more. We propose a simple and natural formalization of sequential decomposition, in which a task is decomposed into two sequential sub-tasks, with the first sub-task to be executed out before the second sub-task is executed. These tasks are specified by means of input/output relations. We define and study decomposition problems, which is to decide whether a given specification can be sequentially decomposed. Our main result is that decomposition itself is a difficult computational problem. More specifically, we study decomposition problems in three settings: where the input task is specified explicitly, by means of Boolean circuits, and by means of automatic relations. We show that in the first setting decomposition is NP-complete, in the second setting it is NEXPTIME-complete, and in the third setting there is evidence to suggest that it is undecidable. Our results indicate that the intuitive idea of decomposition as a system-design approach requires further investigation. In particular, we show that adding human to the loop by asking for a decomposition hint lowers the complexity of decomposition problems considerably.
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spelling oxford-uuid:80106596-3753-441d-bc97-86efbe0bdb242022-03-26T21:20:56ZSequential relational decompositionConference itemhttp://purl.org/coar/resource_type/c_5794uuid:80106596-3753-441d-bc97-86efbe0bdb24Symplectic Elements at OxfordAssociation for Computing Machinery2018Fried, DLegay, AOuaknine, JVardi, MThe concept of decomposition in computer science and engineering is considered a fundamental component of computational thinking and is prevalent in design of algorithms, software construction, hardware design, and more. We propose a simple and natural formalization of sequential decomposition, in which a task is decomposed into two sequential sub-tasks, with the first sub-task to be executed out before the second sub-task is executed. These tasks are specified by means of input/output relations. We define and study decomposition problems, which is to decide whether a given specification can be sequentially decomposed. Our main result is that decomposition itself is a difficult computational problem. More specifically, we study decomposition problems in three settings: where the input task is specified explicitly, by means of Boolean circuits, and by means of automatic relations. We show that in the first setting decomposition is NP-complete, in the second setting it is NEXPTIME-complete, and in the third setting there is evidence to suggest that it is undecidable. Our results indicate that the intuitive idea of decomposition as a system-design approach requires further investigation. In particular, we show that adding human to the loop by asking for a decomposition hint lowers the complexity of decomposition problems considerably.
spellingShingle Fried, D
Legay, A
Ouaknine, J
Vardi, M
Sequential relational decomposition
title Sequential relational decomposition
title_full Sequential relational decomposition
title_fullStr Sequential relational decomposition
title_full_unstemmed Sequential relational decomposition
title_short Sequential relational decomposition
title_sort sequential relational decomposition
work_keys_str_mv AT friedd sequentialrelationaldecomposition
AT legaya sequentialrelationaldecomposition
AT ouakninej sequentialrelationaldecomposition
AT vardim sequentialrelationaldecomposition