# Length Abstraction in Euclidean Geometry

Ketland, Jeffrey (2023) Length Abstraction in Euclidean Geometry. [Preprint]

## Abstract

I define abstract lengths in Euclidean geometry, by introducing an abstraction axiom: $\lambda(a,b) = \lambda(c,d) \iff ab \equiv cd$. By geometric constructions and explicit definitions, one may define the \emph{Length structure}: $\Len = (\Len, \oplus, \preceq, \bigcdot)$, instantiated by Euclidean geometry'', so to speak. I define the notion of a (continuous) positive extensive quantity'' and prove that $\Len$ is such a (continuous) positive extensive quantity. The main results given provide the general characterization of $\Len$ and its symmetry group (the multiplicative group of the positive reals); along with the relevant mathematical relationships between (abstract) lengths and \emph{coordinate} lengths (relative to a coordinate system); and also between lengths, measurement scales and units for length.

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Item Type: Preprint
Creators:
CreatorsEmailORCID
Ketland, Jeffreyjeffreyketland@gmail.com0000-0002-5128-4387
Keywords: Geometry; quantities; measurement; abstraction principle; representation theorem; length
Subjects: Specific Sciences > Physics
General Issues > Structure of Theories
Depositing User: Dr Jeffrey Ketland
Date Deposited: 05 Feb 2023 14:01
Item ID: 21714
Subjects: Specific Sciences > Physics
General Issues > Structure of Theories
Date: 3 February 2023
URI: http://philsci-archive.pitt.edu/id/eprint/21714