Two torus identification problems

In summary, the fundamental group is Z x Z x Z and the homology is H_0(X) = Z, H_1(X) = 0, and H_2(X) = Z.
  • #1
mrbohn1
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0
1. Compute the fundamental group of the space obtained from 2 two-dimensional tori S1 x S1 by identifying a circle S1 x {0} in one torus with the corresponding circle S1 x {0} in the other torus.

Am I right in thinking that the resulting space is S1 x S1 x S1, and hence the fundamental group is Z x Z x Z?

2. Let p and q be integers and let f: S1 x S1 ----> S1 x S1 be given by f(x,y)=(xp,xq) (for x and y complex numbers of magnitude 1).
Let X = D2 x S1 and Y = S1 x D2. Then both spaces have S1 x S1 as a boundary. Form the adjunction space by identifying the boundaries of X and Y using f as the attaching map.
Compute the homology of the resulting space.

I could easily compute the homology here if I knew the cell structure of the resulting space, but I am having trouble visualizing it.

Any help much appreciated!
 
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  • #2
The resulting space is a connected sum of two tori, which is homeomorphic to a sphere. Therefore, its homology is H_0(X) = Z, H_1(X) = 0, and H_2(X) = Z.
 

1. What is a two torus identification problem?

A two torus identification problem is a mathematical problem in topology that involves identifying two surfaces, known as tori, based on their topological properties. The goal is to determine if two given tori are topologically equivalent, meaning they can be continuously deformed into one another without cutting or tearing.

2. How is a two torus identification problem solved?

Two torus identification problems are typically solved using techniques from algebraic topology, such as the fundamental group and homology. These techniques allow for the topological properties of each torus to be compared, and if they are found to be equivalent, the problem is considered solved.

3. What are some applications of two torus identification problems?

Two torus identification problems have applications in various fields, including physics, computer science, and robotics. For example, in physics, these problems can help in understanding the properties of knots and links in DNA molecules. In computer science, they can be used to develop algorithms for image recognition and shape analysis. In robotics, they can aid in the design of efficient and stable robot movements.

4. Are there any real-life examples of two torus identification problems?

One real-life example of a two torus identification problem is the identification of different types of doughnuts. While all doughnuts have a similar shape, they can have different topological properties, such as the number of holes or twists. By solving the two torus identification problem for each doughnut, we can determine the different types of doughnuts that exist.

5. Can two torus identification problems be generalized to higher dimensions?

Yes, two torus identification problems can be generalized to higher dimensions. In fact, the concept of topological equivalence applies to any dimension, not just two-dimensional surfaces. However, as the number of dimensions increases, the complexity of the problem also increases, making it more challenging to solve.

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