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wedge sum

wedge sum

9.9
A shape made by joining several spaces, like two circles, at one point
  • noun
  • Specialized
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  • The wedge sum of two circles looks like a figure-eight.

Examples

  • When considering homotopy groups, the wedge sum can simplify many calculations.

  • We studied the wedge sums in our topology class.

  • In algebraic topology, the wedge sum is frequently used to study spaces built from simpler components.

  • The wedge sum of two spaces can be visualized easily.

  • In algebraic topology, the wedge sum is frequently used to study spaces built from simpler components.

  • The wedge sum of two circles looks like a figure-eight.

  • When considering homotopy groups, the wedge sum can simplify many calculations.

Surface Forms

wedge sum singular
wedge sums plural

Morphology

wedge + sum

The components 'wedge' (suggesting a joining or inserted piece) and 'sum' (a combining or union) give a partial cue that this is a way of combining spaces, so a learner might infer some kind of joining. However, the precise topological meaning — joining a family of spaces at a single common point — is a technical, domain-specific sense that is not fully predictable from the everyday meanings, so the expression is only partly transparent.

Etymology

Wedge sum paints a simple picture: wedge suggests pieces meeting at a point and sum means adding them, so imagine several shapes glued together at one point, like two circles making a figure-eight. That's why the term means 'many spaces joined at a single point'.