Homology calculation using Mayer-Vietoris sequence

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SUMMARY

This discussion focuses on calculating homology groups using the Mayer-Vietoris sequence. The main objective is to demonstrate that ##H_q(X \times S^n, X \times p) \cong H_{q-n}(X)##, where ##p \in S^n## and ##X## is a polyhedron. Participants suggest starting the proof by expressing ##S^n## as the union of its upper and lower hemispheres and recommend using induction on ##n##. The conversation also explores the implications of choosing a polyhedron over simpler shapes like spheres or solid balls.

PREREQUISITES
  • Understanding of homology groups in algebraic topology
  • Familiarity with the Mayer-Vietoris sequence
  • Knowledge of polyhedra and their properties
  • Induction techniques in mathematical proofs
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  • Study the Mayer-Vietoris sequence in detail
  • Explore the properties of homology groups for polyhedra
  • Learn about induction proofs in algebraic topology
  • Investigate the relationship between polyhedra and simpler topological spaces like spheres
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Mathematicians, topologists, and students interested in algebraic topology, particularly those working on homology theory and the application of the Mayer-Vietoris sequence.

PsychonautQQ
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Hey PF! This isn't for homework, just me messing around with some thoughts in caluclating various homology groups.

So suppose we have ##p \in S^n## and suppose that ##X## is a Polyhedra.

I want to show that ##H_q(X \times S^n, X \times p) \cong H_{q-n}(X)##

I was given the hint to start out by writing ##S^n## as the union of upper and lower hemispheres, and to proceed by induction on n.

Can anyone offer some insight?
 
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before i think about this, do you have any response to my answer to your previous question?
 
PsychonautQQ said:
Hey PF! This isn't for homework, just me messing around with some thoughts in caluclating various homology groups.

So suppose we have ##p \in S^n## and suppose that ##X## is a Polyhedra.

I want to show that ##H_q(X \times S^n, X \times p) \cong H_{q-n}(X)##

I was given the hint to start out by writing ##S^n## as the union of upper and lower hemispheres, and to proceed by induction on n.

Can anyone offer some insight?
I've been meaning to have a go at this, but other things keep on getting in the way. A couple of questions first though: Is the polyhedron ##X## a 2D surface or a solid? The former is homeomorphic to the sphere ##S^2## and the latter to the solid ball in 3D space ##B_1((0,0,0))##. Since both are simpler shapes than a polyhedron, it makes me wonder why they specify a polyhedron rather than a sphere or a solid ball. Could it be because they want part of the challenge to be to make the fairly elementary observation that a polyhedral surface is homeomorphic to ##S^2## otr that a solid polyhedron is homeomorphic to a solid ball?
 

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