Topology

Study of geometric properties preserved under continuous deformations.
Basic Concepts

What is Topology?

Understanding Topology

Topology is a branch of mathematics that studies the properties of shapes and spaces that remain unchanged under continuous deformations—like stretching, twisting, and bending, but not tearing or gluing. It’s often called “rubber-sheet geometry” because objects are considered equivalent if they can be transformed into one another by these gentle manipulations.

Key Concepts

  • Continuous deformation: Changing an object’s shape without cutting or attaching new parts.
  • Topological equivalence: Two objects are the same in topology if one can be transformed into the other by bending or stretching.

Why Does It Matter?

Topology helps us understand deep relationships between objects beyond their size or exact shape. It reveals hidden connections in nature, science, and technology.

Everyday Examples

  • A coffee mug and a donut: Both have one hole and can be reshaped into each other by stretching.
  • A basketball and a balloon: Both are simple spheres in topology, regardless of material.

Examples

  • A pretzel and a figure-eight knot are topologically different because one has three holes and the other has one.

  • A square and a circle are topologically the same, since you can deform one into the other without tearing or gluing.

In a Nutshell

Topology studies shapes and spaces that keep their essential properties even when stretched or bent.

Key Terms

Continuous deformation
A smooth transformation of an object that doesn't involve tearing or gluing.
Homeomorphism
A one-to-one, onto, and continuous mapping between two shapes with a continuous inverse.
Topological space
A set of points along with a set of neighborhoods for each point that satisfies certain rules.
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