Alexander Duality & Cup Product: Commuting?

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In summary, the conversation is discussing the relationship between Alexander duality and cup product, specifically in the case of a circle embedded in S3. There is a conjecture that there is a natural homomorphism from H1(C1)xH1(C2) into Z that completes the square, with the degree of the linking map of the torus C1xC2 into the 2 sphere being the key factor.
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wofsy
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does Alexander duality commute with cup product?
 
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How could the dimensions add up? Unless I'm interpreting this the wrong way, taking the cup product of the images would be in a different cohomology group than the image of of the cup product.
 
  • #3
On second thought, I think I can make the dimensions add up if you're also invoking Poincare duality. Can you tell me the statement of Alexander duality that you're using?
 
  • #4
zhentil said:
On second thought, I think I can make the dimensions add up if you're also invoking Poincare duality. Can you tell me the statement of Alexander duality that you're using?

I am really thinking about a special case of Alexander duality, the case of a circle embedded in S3,

H^*(S3-C) iso Hn-*(C)

If there are two embedded circles then cup product maps H^1(S3-C1)xH^1(S3-C2) -> H^2(S3-C1UC2).

The Alexander maps take these two groups into H1(C1)xH1(C2) and H0(C1UC2).
These are ZxZ and Z.

I was really wondering if there is a natural homomorphism from H1(C1)xH1(C2) into Z that completes the square. The conjecture is that it is the degree of the linking map of the torus C1xC2 into the 2 sphere.
 

FAQ: Alexander Duality & Cup Product: Commuting?

1. What is Alexander Duality?

Alexander Duality is a mathematical theorem that relates the homology of a space to the cohomology of its complement. It is a fundamental tool in algebraic topology and has many applications in various fields of mathematics.

2. What is Cup Product?

The Cup Product is a binary operation in cohomology that combines two cohomology classes to produce a third one. It is closely related to the intersection product in topology and has many important properties that make it a powerful tool in algebraic topology.

3. How do Alexander Duality and Cup Product commute?

Alexander Duality and Cup Product commute when applied to certain pairs of spaces. This means that the order in which we apply these two operations does not matter, and we will get the same result regardless. This result is known as the Commutativity Theorem.

4. What are the applications of Alexander Duality and Cup Product?

Alexander Duality and Cup Product have numerous applications in topology, geometry, and algebra. They are used to prove important theorems, such as the Poincaré Duality Theorem and the Lefschetz Fixed Point Theorem, and have applications in fields such as knot theory, algebraic geometry, and differential equations.

5. What are some open problems related to Alexander Duality and Cup Product?

Despite their importance, there are still many open problems and conjectures related to Alexander Duality and Cup Product. Some of these include generalizing the Commutativity Theorem to more general situations, finding new applications in other fields of mathematics, and understanding the connections between these two operations and other mathematical concepts.

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