Abstract: We introduce a notion of decentralized observability for discrete-event systems, which we call joint observability. We prove that checking joint observability of a regular language w.r.t.

Abstract: The purpose of this paper is to gain a better understanding of the structure of undecidable problems in automata theory by investigating the degree of unsolvability of these problems. This ...

(Phys.org) -- As a testament to how differently things work in the quantum and classical regimes, physicists have found that a problem that is easily solved in a classical context cannot be solved at ...

The Post Correspondence Problem (PCP) is an undecidable problem. It asks whether a set of domino-like pairs of strings can be arranged in a sequence so that the top and bottom strings match. There's ...

A mathematical problem is computable, if it can be solved by a computer. Computable problems are also called solvable, decidable, and recursive. Earlier it was believed that all mathematical problems ...

Variational Quantum Algorithms (VQAs) are prime candidates for near-term quantum advantage, yet training them is known to be NP-hard. Here we prove a conditional undecidability result for noiseless, ...