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Research draft

line segment

vr.tr.line-segment · XCT.QLT

Let an agent explain line segments and compute their properties, apply them in geometry and mapping, and separate applied senses such as street segments and transects.

Thing Registry Cross-cutting context

Research draft, second pass

A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.

written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify

Researched by: Claude

Purpose and description

Let an agent explain line segments and compute their properties, apply them in geometry and mapping, and separate applied senses such as street segments and transects.

A part of a straight line bounded by two distinct endpoints and containing every point between them, with a definite length; a directed segment has an orientation, and segments appear as chords of circles, edges of polygons, scale markings on instruments, street segments in mapping and transects in field surveys.

What it is for: Geometry, measurement, mapping and surveying.

It can be compute length, midpoint and direction; test intersection and collinearity; explain chords and polygon edges; separate applied senses.

Distinguishing features

Bounded by two endpoints

Finite length

Straight

Can be directed

What it looks like

Not physical; drawn as a straight stroke between two points.

How it is recognised

Two endpoints

Straight

A ray extends infinitely in one direction

Related models

is a kind of - category

arc

is part of - whole

line

is related to - other mathematical object

binomial coefficient

is related to - street segments in mapping

footpath

In practice

Families and kinds

undirected segments

directed segments and vectors

chords and diameters

polygon edges

applied segments in maps and surveys

Standards and regulation

ISO 80000-2 notation

Geographic data standards for road segments

Failure modes and hazards

Confusing segment, ray and line

Floating point errors in intersection tests

Confusing senses

Also called

scale markingmirror scaledirected line segmentstreet segmenttransectchordbimediansemi-axisceviansagittaapothemsemidiameterstability radiusbaselineunit directed line segment

Where this came from

wikidata · CC0 1.0

Drafted structure

Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.

Compute Properties.

Coordinates suffice.

Length

Length and midpoint.

Length

Length.

  1. What are the length and midpoint of the segment between these points? measurement
  2. What is its direction or slope? measurement

Intersect

Intersection.

Intersect

Intersection.

  1. Do these two segments intersect, and where? measurement
  2. How is numerical robustness ensured? action
Geometry In figures.

Segments build shapes.

Chords

Chords of circles.

Chords

Chords.

  1. What is the length of a chord at this distance from the centre? measurement
  2. Which chord theorems apply? definition

Polygons

Edges.

Polygons

Edges.

  1. How do segments form polygon edges, and how is perimeter computed? definition
  2. When are segments collinear? boundary
Directed Orientation.

Direction matters.

Vectors

Directed segments.

Vectors

Directed segments.

  1. How does a directed segment relate to a vector? definition
  2. What changes when direction is reversed? definition

Notation

Writing segments.

Notation

Notation.

  1. How are segments and their lengths notated? provenance
  2. Which conventions differ by country? provenance
Applied Other senses.

Same word, other fields.

Mapping

Street segments.

Mapping

Street segments.

  1. Is a street or road segment in a map dataset meant? boundary
  2. Which data standard applies? provenance

Survey

Transects and scales.

Survey

Transects and scales.

  1. Is a transect in ecology or a scale marking on an instrument meant? boundary
  2. Which entry fits? action

What the second pass must settle

  • Should vectors be a separate entry?
  • How should geometry libraries be linked?
  • How should mapping senses be split?