Numbers and numerosities
Vieri Benci
TL;DR
The paper develops a comprehensive framework for numerosity theory that extends classical counting to infinite sets while preserving Euclid's principle. It systematically builds and analyzes counting systems, introduces label-trees and the Λ-limit to unify discrete counting with continuum-scale magnitudes, and connects numerosities to ordinal, cardinal, hyperreal, and surreal numbers. A central achievement is constructing a numerosity counting system that yields a real-closed Euclidean line $ extbf{E}$, embedding numerosities into hyperreal and surreal settings and enabling a rich algebraic and measure-theoretic interplay. The work provides both a formal model and explicit computations for numerosities of key sets (e.g., $ extbf{N}$, $ extbf{Q}$, $ extbf{R}$), clarifying how different exponentiations and continuum-sized objects behave under the numerosity perspective, with potential implications for nonstandard analysis and the foundations of counting infinite structures.
Abstract
We develop new aspects of the the of numerosity theory; more exactly, we emphasize its relation with the ordinal numbers, cardinal numbers, hyperreal numbers and surreal numbers. In particular, we combine the notion of numerosity with the idea of continuum and we get a definition of Euclidean line which includes all the sets of infinite numbers mentioned above.
