148,065 research outputs found
On Relaxing Metric Information in Linear Temporal Logic
Metric LTL formulas rely on the next operator to encode time distances,
whereas qualitative LTL formulas use only the until operator. This paper shows
how to transform any metric LTL formula M into a qualitative formula Q, such
that Q is satisfiable if and only if M is satisfiable over words with
variability bounded with respect to the largest distances used in M (i.e.,
occurrences of next), but the size of Q is independent of such distances.
Besides the theoretical interest, this result can help simplify the
verification of systems with time-granularity heterogeneity, where large
distances are required to express the coarse-grain dynamics in terms of
fine-grain time units.Comment: Minor change
Real-time and Probabilistic Temporal Logics: An Overview
Over the last two decades, there has been an extensive study on logical
formalisms for specifying and verifying real-time systems. Temporal logics have
been an important research subject within this direction. Although numerous
logics have been introduced for the formal specification of real-time and
complex systems, an up to date comprehensive analysis of these logics does not
exist in the literature. In this paper we analyse real-time and probabilistic
temporal logics which have been widely used in this field. We extrapolate the
notions of decidability, axiomatizability, expressiveness, model checking, etc.
for each logic analysed. We also provide a comparison of features of the
temporal logics discussed
Complexity of Timeline-Based Planning over Dense Temporal Domains: Exploring the Middle Ground
In this paper, we address complexity issues for timeline-based planning over
dense temporal domains. The planning problem is modeled by means of a set of
independent, but interacting, components, each one represented by a number of
state variables, whose behavior over time (timelines) is governed by a set of
temporal constraints (synchronization rules). While the temporal domain is
usually assumed to be discrete, here we consider the dense case. Dense
timeline-based planning has been recently shown to be undecidable in the
general case; decidability (NP-completeness) can be recovered by restricting to
purely existential synchronization rules (trigger-less rules). In this paper,
we investigate the unexplored area of intermediate cases in between these two
extremes. We first show that decidability and non-primitive recursive-hardness
can be proved by admitting synchronization rules with a trigger, but forcing
them to suitably check constraints only in the future with respect to the
trigger (future simple rules). More "tractable" results can be obtained by
additionally constraining the form of intervals in future simple rules:
EXPSPACE-completeness is guaranteed by avoiding singular intervals,
PSPACE-completeness by admitting only intervals of the forms [0,a] and
[b,[.Comment: In Proceedings GandALF 2018, arXiv:1809.0241
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