PSPACE
View article
Querying Log Data with Metric Temporal Logic Open
We propose a novel framework for ontology-based access to temporal log data using a datalog extension datalogMTL of the Horn fragment of the metric temporal logic MTL. We show that datalogMTL is EXPSPACE-complete even with punctual i…
View article
Ontology-Based Data Access with a Horn Fragment of Metric Temporal Logic Open
We advocate datalogMTL, a datalog extension of a Horn fragment of the metric temporal logic MTL, as a language for ontology-based access to temporal log data. We show that datalogMTL is EXPSPACE-complete even with punctual intervals, in wh…
View article
Quantum computation with indefinite causal structures Open
One way to study the physical plausibility of closed timelike curves (CTCs) is to examine their computational power. This has been done for Deutschian CTCs (D-CTCs) and post-selection CTCs (P-CTCs), with the result that they allow for the …
View article
Model Checking Quantitative Hyperproperties Open
Hyperproperties are properties of sets of computation traces. In this paper, we study quantitative hyperproperties, which we define as hyperproperties that express a bound on the number of traces that may appear in a certain relation. For …
View article
The Complexity of Monitoring Hyperproperties Open
We study the runtime verification of hyperproperties, expressed in the temporal logic HyperLTL, as a means to inspect a system with respect to security polices. Runtime monitors for hyperproperties analyze trace logs that are organized by …
View article
Deciding Hyperproperties Open
Hyperproperties, like observational determinism or symmetry, cannot be expressed as properties of individual computation traces, because they describe a relation between multiple computation traces. HyperLTL is a temporal logic that captur…
View article
Reasoning over Streaming Data in Metric Temporal Datalog Open
We study stream reasoning in datalogMTL—an extension of Datalog with metric temporal operators. We propose a sound and complete stream reasoning algorithm that is applicable to a fragment datalogMTLFP of datalogMTL, in which propagation of…
View article
DatalogMTL: Computational Complexity and Expressive Power Open
We study the complexity and expressive power of DatalogMTL - a knowledge representation language that extends Datalog with operators from metric temporal logic (MTL) and which has found applications in ontology-based data access and stream…
View article
Solution to PSPACE‐Complete Problem Using P Systems with Active Membranes with Time‐Freeness Open
P systems with active membranes are powerful parallel natural computing models, which were inspired by cell structure and behavior. Inspired by the parallel processing of biological information and with the idealistic assumption that each …
View article
The Complexity of LTL on Finite Traces: Hard and Easy Fragments Open
This paper focuses on LTL on finite traces (LTLf) for which satisfiability is known to be PSPACE-complete. However, little is known about the computational properties of fragments of LTLf. In this paper we fill this gap and make the follow…
View article
Multiagent Connected Path Planning: PSPACE-Completeness and How to Deal With It Open
In the Multiagent Connected Path Planning problem (MCPP), a team of agents moving in a graph-represented environment must plan a set of start-goal joint paths which ensures global connectivity at each time step, under some communication mo…
View article
Reachability in Two-Dimensional Unary Vector Addition Systems with States is NL-Complete Open
Blondin et al. showed at LICS 2015 that two-dimensional vector addition systems with states have reachability witnesses of length exponential in the number of states and polynomial in the norm of vectors. The resulting guess-and-verify alg…
View article
All PSPACE-Complete Planning Problems Are Equal but Some Are More Equal than Others Open
Complexity analysis of planning is problematic. Even very simple planning languages are PSPACE-complete, yet cannot model many simple problems naturally. Many languages with much more powerful features are also PSPACE-complete. It is thus …
View article
Tractable Fragments of Datalog with Metric Temporal Operators Open
We study the data complexity of reasoning for several fragments of MTL - an extension of Datalog with metric temporal operators over the rational numbers. Reasoning in the full MTL language is PSPACE-complete, which handicaps its applicati…
View article
Nonunitary quantum computation in the ground space of local Hamiltonians Open
A central result in the study of Quantum Hamiltonian Complexity is that the k-Local hamiltonian problem is QMA-complete. In that problem, we must decide if the lowest eigenvalue of a Hamiltonian is bounded below some value, or above anothe…
View article
Universal trees grow inside separating automata: Quasi-polynomial lower bounds for parity games Open
Several distinct techniques have been proposed to design quasi-polynomial algorithms for solving parity games since the breakthrough result of Calude, Jain, Khoussainov, Li, and Stephan (2017): play summaries, progress measures and registe…
View article
Model checking multi-agent systems against epistemic HS specifications with regular expressions Open
We introduce EHS+, a novel temporal-epistemic logic defined on temporal intervals characterised by regular expressions. We investigate the complexity of verifying multi-agent systems against EHS+ specifications for a number of fragments of…
View article
The weak call-by-value λ-calculus is reasonable for both time and space Open
We study the weak call-by-value λ-calculus as a model for computational complexity theory and establish the natural measures for time and space — the number of beta-reduction steps and the size of the largest term in a computation — as rea…
View article
Streaming Complexity of Approximating Max 2CSP and Max Acyclic Subgraph Open
We study the complexity of estimating the optimum value of a Boolean 2CSP (arity two constraint satisfaction problem) in the single-pass streaming setting, where the algorithm is presented the constraints in an arbitrary order. We give a s…
View article
Super Mario Bros. is Harder/Easier Than We Thought Open
Mario is back! In this sequel, we prove that solving a generalized level of Super Mario Bros. is PSPACE-complete, strengthening the previous NP-hardness result (FUN 2014). Both our PSPACE-hardness and the previous NP-hardness use levels of…
View article
The complexity of interaction Open
In this paper, we analyze the complexity of functional programs written in\nthe interaction-net computation model, an asynchronous, parallel and confluent\nmodel that generalizes linear-logic proof nets. Employing user-defined sized\nand s…
View article
More for free: a dynamic epistemic framework for conformant planning over transition systems* Open
In this article, we introduce a lightweight dynamic epistemic logical framework for automated planning under initial uncertainty. We generalize the standard conformant planning problem in AI (over transition systems) in two crucial aspects…
View article
Parameterized verification under TSO is PSPACE-complete Open
We consider parameterized verification of concurrent programs under the Total Store Order (TSO) semantics. A program consists of a set of processes that share a set of variables on which they can perform read and write operations. We show …
View article
Completeness for First-order Properties on Sparse Structures with Algorithmic Applications Open
Properties definable in first-order logic are algorithmically interesting for both theoretical and pragmatic reasons. Many of the most studied algorithmic problems, such as Hitting Set and Orthogonal Vectors, are first-order, and the first…
View article
qbf2epr: A Tool for Generating EPR Formulas from QBF Open
We present the tool qbf2epr which translates quantified Boolean formulas (QBF) to formulas in effectively propositional logic (EPR). The decision problem of QBF is the prototypical problem for PSPACE, whereas EPR is NEXPTIME-complete. Thus…
View article
Window Parity Games: An Alternative Approach Toward Parity Games with Time Bounds Open
Classical objectives in two-player zero-sum games played on graphs often deal\nwith limit behaviors of infinite plays: e.g., mean-payoff and total-payoff in\nthe quantitative setting, or parity in the qualitative one (a canonical way to\ne…
View article
On the Reversibility of Actions in Planning Open
Checking whether action effects can be undone is an important question for determining, for instance, whether a planning task has dead-ends. In this paper, we investigate the reversibility of actions, that is, when the effects of an action…
View article
Perfect half space games Open
We introduce perfect half space games, in which the goal of Player 2 is to make the sums of encountered multidimensional weights diverge in a direction which is consistent with a chosen sequence of perfect half spaces (chosen dynamically b…
View article
Learning Description Logic Concepts: When can Positive and Negative Examples be Separated? Open
Learning description logic (DL) concepts from positive and negative examples given in the form of labeled data items in a KB has received significant attention in the literature. We study the fundamental question of when a separating DL co…
View article
Black Holes and Complexity Classes Open
It is not known what the limitations are on using quantum computation to speed up classical computation. An example would be the power to speed up PSPACE-complete computations. It is also not known what the limitations are on the duration …