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Documents authored by Micheli, Andrea


Document
Introducing Interdependent Simple Temporal Networks with Uncertainty for Multi-Agent Temporal Planning

Authors: Ajdin Sumic, Thierry Vidal, Andrea Micheli, and Alessandro Cimatti

Published in: LIPIcs, Volume 318, 31st International Symposium on Temporal Representation and Reasoning (TIME 2024)


Abstract
Simple Temporal Networks with Uncertainty are a powerful and widely used formalism for representing and reasoning over convex temporal constraints in the presence of uncertainty called contingent constraints. Since their introduction, they have been used in planning and scheduling applications to model situations where the scheduling agent does not control some activity durations or event timings. What needs to be checked is then the controllability of the network, i.e., that there is a valid execution strategy whatever the values of the contingents. This paper considers a new type of multi-agent extension, where, as opposed to previous works, each agent manages its own separate STNU, and the control over activity durations is shared among the agents: what is called here a contract is a mutual constraint controllable for some agent and contingent for others. We will propose a semantically enriched version of STNUs that will be composed into a global Multi-agent Interdependent STNUs model. Then, controllability issues will be revisited, and we will focus on the repair problem, i.e., how to regain failed controllability by shrinking some of the shared contract durations, here in a centralized manner.

Cite as

Ajdin Sumic, Thierry Vidal, Andrea Micheli, and Alessandro Cimatti. Introducing Interdependent Simple Temporal Networks with Uncertainty for Multi-Agent Temporal Planning. In 31st International Symposium on Temporal Representation and Reasoning (TIME 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 318, pp. 13:1-13:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{sumic_et_al:LIPIcs.TIME.2024.13,
  author =	{Sumic, Ajdin and Vidal, Thierry and Micheli, Andrea and Cimatti, Alessandro},
  title =	{{Introducing Interdependent Simple Temporal Networks with Uncertainty for Multi-Agent Temporal Planning}},
  booktitle =	{31st International Symposium on Temporal Representation and Reasoning (TIME 2024)},
  pages =	{13:1--13:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-349-2},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{318},
  editor =	{Sala, Pietro and Sioutis, Michael and Wang, Fusheng},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TIME.2024.13},
  URN =		{urn:nbn:de:0030-drops-212200},
  doi =		{10.4230/LIPIcs.TIME.2024.13},
  annote =	{Keywords: Temporal constraints satisfaction, uncertainty, STNU, Controllability checking, Explainable inconsistency, Multi-agent planning}
}
Document
Efficient Anytime Computation and Execution of Decoupled Robustness Envelopes for Temporal Plans

Authors: Michael Cashmore, Alessandro Cimatti, Daniele Magazzeni, Andrea Micheli, and Parisa Zehtabi

Published in: LIPIcs, Volume 206, 28th International Symposium on Temporal Representation and Reasoning (TIME 2021)


Abstract
One of the major limitations for the employment of model-based planning and scheduling in practical applications is the need of costly re-planning when an incongruence between the observed reality and the formal model is encountered during execution. Robustness Envelopes characterize the set of possible contingencies that a plan is able to address without re-planning, but their exact computation is expensive; furthermore, general robustness envelopes are not amenable for efficient execution. In this paper, we present a novel, anytime algorithm to approximate Robustness Envelopes, making them scalable and executable. This is proven by an experimental analysis showing the efficiency of the algorithm, and by a concrete case study where the execution of robustness envelopes significantly reduces the number of re-plannings.

Cite as

Michael Cashmore, Alessandro Cimatti, Daniele Magazzeni, Andrea Micheli, and Parisa Zehtabi. Efficient Anytime Computation and Execution of Decoupled Robustness Envelopes for Temporal Plans. In 28th International Symposium on Temporal Representation and Reasoning (TIME 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 206, pp. 13:1-13:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)


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@InProceedings{cashmore_et_al:LIPIcs.TIME.2021.13,
  author =	{Cashmore, Michael and Cimatti, Alessandro and Magazzeni, Daniele and Micheli, Andrea and Zehtabi, Parisa},
  title =	{{Efficient Anytime Computation and Execution of Decoupled Robustness Envelopes for Temporal Plans}},
  booktitle =	{28th International Symposium on Temporal Representation and Reasoning (TIME 2021)},
  pages =	{13:1--13:14},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-206-8},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{206},
  editor =	{Combi, Carlo and Eder, Johann and Reynolds, Mark},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TIME.2021.13},
  URN =		{urn:nbn:de:0030-drops-147895},
  doi =		{10.4230/LIPIcs.TIME.2021.13},
  annote =	{Keywords: Temporal Planning, Robustness Envelopes}
}
Document
Olisipo: A Probabilistic Approach to the Adaptable Execution of Deterministic Temporal Plans

Authors: Tomás Ribeiro, Oscar Lima, Michael Cashmore, Andrea Micheli, and Rodrigo Ventura

Published in: LIPIcs, Volume 206, 28th International Symposium on Temporal Representation and Reasoning (TIME 2021)


Abstract
The robust execution of a temporal plan in a perturbed environment is a problem that remains to be solved. Perturbed environments, such as the real world, are non-deterministic and filled with uncertainty. Hence, the execution of a temporal plan presents several challenges and the employed solution often consists of replanning when the execution fails. In this paper, we propose a novel algorithm, named Olisipo, which aims to maximise the probability of a successful execution of a temporal plan in perturbed environments. To achieve this, a probabilistic model is used in the execution of the plan, instead of in the building of the plan. This approach enables Olisipo to dynamically adapt the plan to changes in the environment. In addition to this, the execution of the plan is also adapted to the probability of successfully executing each action. Olisipo was compared to a simple dispatcher and it was shown that it consistently had a higher probability of successfully reaching a goal state in uncertain environments, performed fewer replans and also executed fewer actions. Hence, Olisipo offers a substantial improvement in performance for disturbed environments.

Cite as

Tomás Ribeiro, Oscar Lima, Michael Cashmore, Andrea Micheli, and Rodrigo Ventura. Olisipo: A Probabilistic Approach to the Adaptable Execution of Deterministic Temporal Plans. In 28th International Symposium on Temporal Representation and Reasoning (TIME 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 206, pp. 15:1-15:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)


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@InProceedings{ribeiro_et_al:LIPIcs.TIME.2021.15,
  author =	{Ribeiro, Tom\'{a}s and Lima, Oscar and Cashmore, Michael and Micheli, Andrea and Ventura, Rodrigo},
  title =	{{Olisipo: A Probabilistic Approach to the Adaptable Execution of Deterministic Temporal Plans}},
  booktitle =	{28th International Symposium on Temporal Representation and Reasoning (TIME 2021)},
  pages =	{15:1--15:15},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-206-8},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{206},
  editor =	{Combi, Carlo and Eder, Johann and Reynolds, Mark},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TIME.2021.15},
  URN =		{urn:nbn:de:0030-drops-147913},
  doi =		{10.4230/LIPIcs.TIME.2021.15},
  annote =	{Keywords: Temporal Planning, Temporal Plan Execution, Robotics}
}
Document
SMT-Based Model Checking of Max-Plus Linear Systems

Authors: Muhammad Syifa'ul Mufid, Andrea Micheli, Alessandro Abate, and Alessandro Cimatti

Published in: LIPIcs, Volume 203, 32nd International Conference on Concurrency Theory (CONCUR 2021)


Abstract
Max-Plus Linear (MPL) systems are an algebraic formalism with practical applications in transportation networks, manufacturing and biological systems. MPL systems can be naturally modeled as infinite-state transition systems, and exhibit interesting structural properties (e.g. periodicity or steady state), for which analysis methods have been recently proposed. In this paper, we tackle the open problem of specifying and analyzing user-defined temporal properties for MPL systems. We propose Time-Difference LTL (TDLTL), a logic that encompasses the delays between the discrete-time events governed by an MPL system, and characterize the problem of model checking TDLTL over MPL. We propose a family of specialized algorithms leveraging the periodic behaviour of an MPL system. We prove soundness and completeness, showing that the transient and cyclicity of the MPL system induce a completeness threshold for the verification problem. The algorithms are cast in the setting of SMT-based verification of infinite-state transition systems over the reals, with variants depending on the (incremental vs upfront) computation of the bound, and on the (explicit vs implicit) unrolling of the transition relation. Our comprehensive experiments show that the proposed techniques can be applied to MPL systems of large dimensions and on general TDLTL formulae, with remarkable performance gains against a dedicated abstraction-based technique and a translation to the nuXmv symbolic model checker.

Cite as

Muhammad Syifa'ul Mufid, Andrea Micheli, Alessandro Abate, and Alessandro Cimatti. SMT-Based Model Checking of Max-Plus Linear Systems. In 32nd International Conference on Concurrency Theory (CONCUR 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 203, pp. 22:1-22:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)


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@InProceedings{mufid_et_al:LIPIcs.CONCUR.2021.22,
  author =	{Mufid, Muhammad Syifa'ul and Micheli, Andrea and Abate, Alessandro and Cimatti, Alessandro},
  title =	{{SMT-Based Model Checking of Max-Plus Linear Systems}},
  booktitle =	{32nd International Conference on Concurrency Theory (CONCUR 2021)},
  pages =	{22:1--22:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-203-7},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{203},
  editor =	{Haddad, Serge and Varacca, Daniele},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2021.22},
  URN =		{urn:nbn:de:0030-drops-143993},
  doi =		{10.4230/LIPIcs.CONCUR.2021.22},
  annote =	{Keywords: Max-Plus Linear Systems, Satisfiability Modulo Theory, Model Checking, Linear Temporal Logic}
}
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