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Finite-domain constraint satisfaction problems are either solvable by Datalog, or not even expressible in fixed-point logic with counting. The border between the two regimes coincides with an important dichotomy in universal algebra; in…

Logic · Mathematics 2022-06-08 Manuel Bodirsky , Jakub Rydval

We construct a class of closed timelike curves (CTCs) using a compactified extra dimension $u$. A nonzero metric element $g_{tu}(u)$ enables particles to travel backwards in global time $t$. The compactified dimension guarantees that the…

General Relativity and Quantum Cosmology · Physics 2015-06-11 Chiu Man Ho , Thomas J. Weiler

One out of many emerging implications from solutions of Einstein's general relativity equations are closed timelike curves (CTCs), which are trajectories through spacetime that allow for time travel to the past without exceeding the speed…

General Relativity and Quantum Cosmology · Physics 2019-02-13 Małgorzata Bartkiewicz , Andrzej Grudka , Ryszard Horodecki , Justyna Łodyga , Jacek Wychowaniec

Counterfactual statements, which describe events that did not or cannot take place, are beneficial to numerous NLP applications. Hence, we consider the problem of counterfactual detection (CFD) and seek to enhance the CFD models. Previous…

Computation and Language · Computer Science 2024-10-01 Thong Nguyen , Truc-My Nguyen

Most traditional models of uncertainty have focused on the associational relationship among variables as captured by conditional dependence. In order to successfully manage intelligent systems for decision making, however, we must be able…

Artificial Intelligence · Computer Science 2015-05-19 David Heckerman , Ross D. Shachter

Boolean circuits abstract away from physical details to focus on the logical structure and computational behaviour of digital components. Although such circuits have been studied for many decades, compositionality has been widely ignored or…

Logic in Computer Science · Computer Science 2026-03-24 Damian Arellanes

We present characterisations of "exact" gap-definable classes, in terms of indeterministic models of computation which slightly modify the standard model of quantum computation. This follows on work of Aaronson [arXiv:quant-ph/0412187], who…

Computational Complexity · Computer Science 2015-09-28 Niel de Beaudrap

We introduce a notion of complexity of diagrams (and in particular of objects and morphisms) in an arbitrary category, as well as a notion of complexity of functors between categories equipped with complexity functions. We discuss several…

Category Theory · Mathematics 2020-07-01 Saugata Basu , M. Umut Isik

The class $\mathcal{UP}$ of `ultimate polynomial time' problems over $\mathbb C$ is introduced; it contains the class $\mathcal P$ of polynomial time problems over $\mathbb C$. The $\tau$-Conjecture for polynomials implies that…

Numerical Analysis · Mathematics 2025-10-20 Gregorio Malajovich

Functional reactive programming (FRP) makes it possible to express temporal aspects of computations in a declarative way. Recently we developed two kinds of categorical models of FRP: abstract process categories (APCs) and concrete process…

Programming Languages · Computer Science 2014-06-10 Wolfgang Jeltsch

Adaptive Conformal Inference (ACI) provides finite-sample coverage guarantees, enhancing the prediction reliability under non-exchangeability. This study demonstrates that these desirable properties of ACI do not require the use of…

Machine Learning · Statistics 2025-07-02 Johan Hallberg Szabadváry , Tuwe Löfström

We investigate the computational power of particle methods, a well-established class of algorit hms with applications in scientific computing and computer simulation. The computational power of a compute model determines the class of…

Formal Languages and Automata Theory · Computer Science 2025-07-23 Johannes Pahlke , Ivo F. Sbalzarini

Research on indefinite causal structures is a rapidly evolving field that has a potential not only to make a radical revision of the classical understanding of space-time but also to achieve enhanced functionalities of quantum information…

Quantum Physics · Physics 2021-10-08 Martin J. Renner , Časlav Brukner

We show that the explicit realization of data-driven predictive control (DPC) for linear deterministic systems is more tractable than previously thought. To this end, we compare the optimal control problems (OCP) corresponding to…

Systems and Control · Electrical Eng. & Systems 2023-04-18 Manuel Klädtke , Dieter Teichrib , Nils Schlüter , Moritz Schulze Darup

Concept-based models are an emerging paradigm in deep learning that constrains the inference process to operate through human-interpretable variables, facilitating explainability and human interaction. However, these architectures, on par…

Distributional robustness is a central goal of prediction algorithms due to the prevalent distribution shifts in real-world data. The prediction model aims to minimize the worst-case risk among a class of distributions, a.k.a., an…

Machine Learning · Statistics 2025-05-20 Marin Šola , Peter Bühlmann , Xinwei Shen

Non-convex optimization problems often arise from probabilistic modeling, such as estimation of posterior distributions. Non-convexity makes the problems intractable, and poses various obstacles for us to design efficient algorithms. In…

Machine Learning · Computer Science 2013-12-18 Khoat Than , Tu Bao Ho

Causal modelling provides a powerful set of tools for identifying causal structure from observed correlations. It is well known that such techniques fail for quantum systems, unless one introduces `spooky' hidden mechanisms. Whether one can…

Quantum Physics · Physics 2016-06-28 Fabio Costa , Sally Shrapnel

The conceptual definition and understanding of time, both quantitatively and qualitatively is of the utmost difficulty and importance. As time is incorporated into the proper structure of the fabric of spacetime, it is interesting to note…

General Relativity and Quantum Cosmology · Physics 2013-10-21 Francisco S. N. Lobo

Dynamical Systems theory generally deals with fixed point iterations of continuous functions. Computation by Turing machine although is a fixed point iteration but is not continuous. This specific category of fixed point iterations can only…

Other Computer Science · Computer Science 2014-10-31 Nabarun Mondal , Partha P. Ghosh