# What is the difference between homotopy and homology?

## What is the difference between homotopy and homology?

In topology|lang=en terms the difference between homotopy and homology. is that homotopy is (topology) a system of groups associated to a topological space while homology is (topology) a theory associating a system of groups to each topological space.

## What is null homotopy?

A continuous map. between topological spaces is said to be null-homotopic if it is homotopic to a constant map. If a space has the property that , the identity map on , is null-homotopic, then. is contractible.

What is homotopic in complex analysis?

Two mathematical objects are said to be homotopic if one can be continuously deformed into the other. For example, the real line is homotopic to a single point, as is any tree. However, the circle is not contractible, but is homotopic to a solid torus. The basic version of homotopy is between maps.

### Is homotopy continuous?

Two continuous functions from one topological space to another are called homo- topic if one can be “continuously deformed” into the other, such a deformation being called a homotopy between the two functions. More precisely, we have the following definition.

### Is homotopy equivalence Bijective?

When two spaces X and X′ become homotopy equivalent after one suspension, the homotopy equivalence between the suspensions will induce a bijection between the towers {[ΣX, Y(n)]} and {[ΣX′, Y(n)]}, with the two properties just mentioned. This bijection is not necessarily a group isomorphism however.

Is a retraction a homotopy equivalence?

Deformation retraction is a particular case of homotopy equivalence. In fact, two spaces are homotopy equivalent if and only if they are both homeomorphic to deformation retracts of a single larger space. Any topological space that deformation retracts to a point is contractible and vice versa.

#### Who introduced homotopy?

Introduction In recent years, the homotopy perturbation method (HPM), first proposed by Dr. Ji Huan He [1], [2], has successfully been applied to solve many types of linear and nonlinear functional equations.

#### What is the meaning of homotopy perturbation method?

The homotopy perturbation method is a powerful and efficient technique for finding solutions of nonlinear equations without the need of a linearization process. The method was first introduced by He in 1998 [1], [2]. HPM is a combination of the perturbation and homotopy methods.

Is a circle homotopy equivalent to a point?

Disclaimer: OBVIOUSLY a circle is NOT homotopic to a point. However, if we just pick one point x0 from S1, then the mapping cylinder looks just like a cone, with F(x,0)=x, F(x0,t)=x0 (which is a line going down the cone from the circle to the bottom apex), and F(x,1)=x0.

## When do you use the term pointed homotopy?

Also, if g is a retraction from X to K and f is the identity map, this is known as a strong deformation retract of X to K . When K is a point, the term pointed homotopy is used.

## When is a homotopy called a nullhomotopic?

A map is called nullhomotopicwhen it is homotopic to a constant map. A space is called contractiblewhen the identity map from the space to itself is nullhomotopic. For example, each real topological vector space is contractible – a suitable homotopy is given by F(x,t) = (1-t)x.

When do two spaces have the same homotopy type?

Given two spaces X and Y, we say they are homotopy equivalent, or of the same homotopy type, if there exist continuous maps f : X → Y and g : Y → X such that g ∘ f is homotopic to the identity map id X and f ∘ g is homotopic to id Y. The maps f and g are called homotopy equivalences in this case.

### Which is the homotopy equivalence between X and Y?

Given two topological spaces X and Y, a homotopy equivalence between X and Y is a pair of continuous maps f : X → Y and g : Y → X, such that g ∘ f is homotopic to the identity map id X and f ∘ g is homotopic to id Y. If such a pair exists, then X and Y are said to be homotopy equivalent, or of the same homotopy type.

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