A Sound-and-Complete Propagation-Based Algorithm for Checking the Dynamic Consistency of Conditional Simple Temporal Networks

Hunsberger, Luke; Posenato, Roberto; Combi, Carlo

doi:10.1109/time.2015.26

Cited by 29 publications

(34 citation statements)

References 6 publications

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“…Later on, those conditions have been analyzed and formalized in Hunsberger et al (2012) and in Hunsberger et al (2015), leading to the sound notion of Conditional Simple Temporal Network (CSTN). In more details, in Hunsberger et al (2015) both time-point (nodes) and constraints (edges) of a CSTN can have propositional labels-for specifying in which scenarios they have to be considered-and such labels have to satisfy some well-definedness properties, in order to guarantee that a dynamic execution strategy can exists. Finally, in Hunsberger et al (2015) authors proposed a sound-and-complete algorithm for solving CSTP showing-by an experimental evaluation-its good performance.…”

Section: Motivations and Related Workmentioning

confidence: 99%

“…To the best of our knowledge, the first work to approach a notion of DC with an instantaneous reaction-time is Hunsberger et al (2015), where the corresponding notion was named IR-DC (DC with instantaneous reaction). The aim was to offer a sound-and-complete propagation-based DC-checking algorithm for CSTNs.…”

Section: Motivations and Related Workmentioning

confidence: 99%

“…The aim was to offer a sound-and-complete propagation-based DC-checking algorithm for CSTNs. The subsequent work Hunsberger and Posenato (2016) extended and amended Hunsberger et al (2015) so that to check ε-DC, both for ε > 0 and for ε = 0. However, to the best of our knowledge, the worst-case complexity of those algorithms is currently unsettled.…”

Section: Motivations and Related Workmentioning

confidence: 99%

“…1 (i.e., the one which is scheduled at time t = 0). In all of the following definitions, which basically come from (Tsamardinos et al, 2003;Hunsberger et al, 2015), we shall implicitly refer to some CSTN Γ = (V, A, L, O, OV, P ).…”

Section: Conditional Simple Temporal Networkmentioning

confidence: 99%

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Instantaneous Reaction-Time in Dynamic-Consistency Checking of Conditional Simple Temporal Networks

Cairo

Comin

Rizzi

2016

2016 23rd International Symposium on Temporal Representation and Reasoning (TIME)

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International audienceConditional Simple Temporal Network CSTN is a constraint-based graph-formalism for conditional temporal planning. Three notions of consistency arise for CSTNs and CSTPs: weak, strong, and dynamic. Dynamic-Consistency (DC) is the most interesting notion, but it is also the most challenging. In order to address the DC-Checking problem, in [Comin and Rizzi, TIME 2015] we introduced ε-DC (a refined, more realistic, notion of DC), and provided an algorithmic solution to it. Next, given that DC implies ε-DC for some sufficiently small ε > 0, and that for every ε > 0 it holds that ε-DC implies DC, we offered a sharp lower bounding analysis on the critical value of the reaction-time ε under which the two notions coincide. This delivered the first (pseudo) singly-exponential time algorithm for the DC-Checking of CSTNs. However, the ε-DC notion is interesting per se, and the ε-DC-Checking algorithm in [Comin and Rizzi, TIME 2015] rests on the assumption that the reaction-time satisfies ε > 0, leaving unsolved the question of what happens when ε = 0. In this work, we introduce and study π-DC, a sound notion of DC with an instantaneous reaction-time (i.e. one in which the planner can react to any observation at the same instant of time in which the observation is made). Firstly, we demonstrate by a counter-example that π-DC is not equivalent to 0-DC, and that 0-DC is actually inadequate for modeling DC with an instantaneous reaction-time. This shows that the main results obtained in our previous work do not apply directly, as they were formulated, to the case of ε = 0. Motivated by this observation, as a second contribution, our previous tools are extended in order to handle π-DC, and the notion of ps-tree is introduced, also pointing out a relationship between π-DC and HyTN-Consistency. Thirdly, a simple reduction from π-DC-Checking to DC-Checking is identified. This allows us to design and to analyze the first sound-and-complete π-DC-Checking procedure. Remarkably, the time complexity of the proposed algorithm remains (pseudo) singly-exponential in the number of propositional letters

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Section: Motivations and Related Workmentioning

confidence: 99%

Section: Motivations and Related Workmentioning

confidence: 99%

Section: Motivations and Related Workmentioning

confidence: 99%

Section: Conditional Simple Temporal Networkmentioning

confidence: 99%

See 2 more Smart Citations

Instantaneous Reaction-Time in Dynamic-Consistency Checking of Conditional Simple Temporal Networks

Cairo

Comin

Rizzi

2016

2016 23rd International Symposium on Temporal Representation and Reasoning (TIME)

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“…In this section, Conditional Simple Temporal Networks (CSTNs) and their dynamic controllability are formally defined. The definitions are taken from [7].…”

Section: Introductionmentioning

confidence: 99%

Dynamic Controllability of Conditional Simple Temporal Networks Is PSPACE-complete

Cairo

Rizzi

2016

2016 23rd International Symposium on Temporal Representation and Reasoning (TIME)

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Even after the proposal of various solution algorithms, the precise computational complexity of checking whether a Conditional Temporal Network is Dynamically Controllable had still remained widely open. This issue gets settled in this paper which provides constructions, algorithms, and bridging lemmas and arguments to formally prove that:(1) the problem is PSPACE-hard, and (2) the problem lies in PSPACE.1 The term "dynamic consistency" is sometimes used in the context of CSTNs. We prefer to use "dynamic controllability" to emphasize the active role of the planner and to match the name used in the literature for other type of temporal networks, such as STNUs.

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Conditional Uncertainty in Constraint Networks

Zavatteri

Viganò

2018

Lecture Notes in Computer Science

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A Sound-and-Complete Propagation-Based Algorithm for Checking the Dynamic Consistency of Conditional Simple Temporal Networks

Cited by 29 publications

References 6 publications

Instantaneous Reaction-Time in Dynamic-Consistency Checking of Conditional Simple Temporal Networks

Instantaneous Reaction-Time in Dynamic-Consistency Checking of Conditional Simple Temporal Networks

Dynamic Controllability of Conditional Simple Temporal Networks Is PSPACE-complete

Conditional Uncertainty in Constraint Networks

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