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We analyze two types of relativistic simultaneity associated to an observer: the spacelike simultaneity, given by Landau submanifolds, and the lightlike simultaneity (also known as observed simultaneity), given by past-pointing horismos…

General Relativity and Quantum Cosmology · Physics 2014-11-17 V. J. Bolos , V. Liern , J. Olivert

Multidimensional unfolding methods are widely used for visualizing item response data. Such methods project respondents and items simultaneously onto a low-dimensional Euclidian space, in which respondents and items are represented by ideal…

Methodology · Statistics 2020-09-04 Yunxiao Chen , Zhiliang Ying , Haoran Zhang

We briefly review two recently developed extensions of the Lorentzian geometry of spacetime and prove that they are in fact closely related. The first is the concept of observer space, which generalizes the space of Lorentzian observers,…

General Relativity and Quantum Cosmology · Physics 2013-06-28 Manuel Hohmann

In this paper we give a geometrical framework for the design of observers on finite-dimensional Lie groups for systems which possess some specific symmetries. The design and the error (between true and estimated state) equation are explicit…

Optimization and Control · Mathematics 2016-11-15 S. Bonnabel , P. Martin , P. Rouchon

We work on a 4-manifold equipped with Lorentzian metric $g$ and consider a volume-preserving diffeomorphism which is the unknown quantity of our mathematical model. The diffeomorphism defines a second Lorentzian metric $h$, the pullback of…

Mathematical Physics · Physics 2021-01-05 Matteo Capoferri , Dmitri Vassiliev

The static, apparently cylindrically symmetric vacuum solution of Linet and Tian for the case of a positive cosmological constant $\Lambda$ is shown to have toroidal symmetry and, besides $\Lambda$, to include three arbitrary parameters. It…

General Relativity and Quantum Cosmology · Physics 2010-12-23 J. B. Griffiths , J. Podolsky

In complex general relativity, Lorentzian space-time is replaced by a four-complex-dimensional complex-Riemannian manifold, with holomorphic connection and holomorphic curvature tensor. A multisymplectic analysis shows that the Hamiltonian…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Giampiero Esposito

Quantified Boolean logic results from adding operators to Boolean logic for existentially and universally quantifying variables. This extends the reach of Boolean logic by enabling a variety of applications that have been explored over the…

Artificial Intelligence · Computer Science 2021-10-13 Adnan Darwiche , Pierre Marquis

A straightforward argument shows that, by allowing counterfactual elements of physical reality, any arbitrary discrete finite-dimensional operator corresponds to an observable.

Quantum Physics · Physics 2007-05-23 Karl Svozil

Partition logics -- non-Boolean event structures obtained by pasting Boolean algebras -- provide a natural language for situations in which a system has a definite latent state but can be accessed and resolved only through mutually…

Physics and Society · Physics 2026-04-01 Karl Svozil

We present an algebraic view on logic programming, related to proof theory and more specifically linear logic and geometry of interaction. Within this construction, a characterization of logspace (deterministic and non-deterministic)…

Logic in Computer Science · Computer Science 2014-06-10 Clément Aubert , Marc Bagnol , Paolo Pistone , Thomas Seiller

This work presents an operational and geometric approach to logic. It starts from the multilinear elective decomposition of binary logical functions in the original form introduced by George Boole. A justification on historical grounds is…

Logic in Computer Science · Computer Science 2018-02-07 Zeno Toffano

We study visual representation learning from a structural and topological perspective. We begin from a single hypothesis: that visual understanding presupposes a semantic language for vision, in which many perceptual observations correspond…

Computer Vision and Pattern Recognition · Computer Science 2026-01-01 Xiu Li

The area of research called \textquotedblleft Lineability\textquotedblright% \ looks for linear structures inside exotic subsets of vector spaces. In the last decade lineability/spaceability has been investigated in rather general settings;…

Functional Analysis · Mathematics 2018-09-10 Vinícius Fávaro , Daniel Pellegrino , Daniel Tomaz

We study the state estimation problem for linear control systems with quadratic outputs which are locally unobservable at the equilibrium. We show that, despite this inherent lack of observability, an adversary with sensor read and write…

Optimization and Control · Mathematics 2026-05-11 Zeyad M. Manaa , Nathan van de Wouw , Michelle S. Chong

We use functions of a bicomplex variable to unify the existing constructions of harmonic morphisms from a 3-dimensional Euclidean or pseudo-Euclidean space to a Riemannian or Lorentzian surface. This is done by using the notion of…

Differential Geometry · Mathematics 2010-03-12 Paul Baird , John C. Wood

We address the problem of learning representations from observations of a scene involving an agent and an external object the agent interacts with. To this end, we propose a representation learning framework extracting the location in…

Machine Learning · Computer Science 2023-09-12 Alfredo Reichlin , Giovanni Luca Marchetti , Hang Yin , Anastasiia Varava , Danica Kragic

We present a unified framework for studying the identifiability of representations learned from simultaneously observed views, such as different data modalities. We allow a partially observed setting in which each view constitutes a…

Invariant object recognition is one of the most fundamental cognitive tasks performed by the brain. In the neural state space, different objects with stimulus variabilities are represented as different manifolds. In this geometrical…

Neurons and Cognition · Quantitative Biology 2021-06-03 SueYeon Chung

We aim to completely formalize the rough topological analysis of integrable Hamiltonian systems admitting analytical solutions such that the initial phase variables along with the time derivatives of the auxiliary variables are expressed as…

Exactly Solvable and Integrable Systems · Physics 2013-09-30 Mikhail P. Kharlamov