*Friedhelm Waldhausen, Bjørn Jahren, and John Rognes*

- Published in print:
- 2013
- Published Online:
- October 2017
- ISBN:
- 9780691157757
- eISBN:
- 9781400846528
- Item type:
- chapter

- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691157757.003.0003
- Subject:
- Mathematics, Geometry / Topology

This chapter deals with simple maps of finite simplicial sets, along with some of their formal properties. It begins with a discussion of simple maps of simplicial sets, presenting a proposition for ...
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This chapter deals with simple maps of finite simplicial sets, along with some of their formal properties. It begins with a discussion of simple maps of simplicial sets, presenting a proposition for the conditions that qualify a map of finite simplicial sets as a simple map. In particular, it considers a simple map as a weak homotopy equivalence. Weak homotopy equivalences have the 2-out-of-3 property, which combines the composition, right cancellation and left cancellation properties. The chapter proceeds by defining some relevant terms, such as Euclidean neighborhood retract, absolute neighborhood retract, Čech homotopy type, and degeneracy operator. It also describes normal subdivision of simplicial sets, geometric realization and subdivision, the reduced mapping cylinder, how to make simplicial sets non-singular, and the approximate lifting property.Less

This chapter deals with simple maps of finite simplicial sets, along with some of their formal properties. It begins with a discussion of simple maps of simplicial sets, presenting a proposition for the conditions that qualify a map of finite simplicial sets as a simple map. In particular, it considers a simple map as a weak homotopy equivalence. Weak homotopy equivalences have the 2-out-of-3 property, which combines the composition, right cancellation and left cancellation properties. The chapter proceeds by defining some relevant terms, such as Euclidean neighborhood retract, absolute neighborhood retract, Čech homotopy type, and degeneracy operator. It also describes normal subdivision of simplicial sets, geometric realization and subdivision, the reduced mapping cylinder, how to make simplicial sets non-singular, and the approximate lifting property.

*Friedhelm Waldhausen, Bjørn Jahren, and John Rognes*

- Published in print:
- 2013
- Published Online:
- October 2017
- ISBN:
- 9780691157757
- eISBN:
- 9781400846528
- Item type:
- chapter

- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691157757.003.0004
- Subject:
- Mathematics, Geometry / Topology

Abstract and Keywords to be supplied.

Abstract and Keywords to be supplied.

*Friedhelm Waldhausen, Bjørn Jahren, and John Rognes*

- Published in print:
- 2013
- Published Online:
- October 2017
- ISBN:
- 9780691157757
- eISBN:
- 9781400846528
- Item type:
- chapter

- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691157757.003.0005
- Subject:
- Mathematics, Geometry / Topology

This chapter reduces the proof of the manifold part of the stable parametrized h-cobordism theorem to a result about spaces of stably framed manifolds. Here Δsuperscript q denotes the standard ...
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This chapter reduces the proof of the manifold part of the stable parametrized h-cobordism theorem to a result about spaces of stably framed manifolds. Here Δsuperscript q denotes the standard affine q-simplex. All polyhedra will be compact, and all manifolds considered will be compact PL manifolds. The chapter begins with a discussion of spaces of PL manifolds. It defines a space of manifolds as a simplicial set, with families of manifolds parametrized by Δsuperscript q as the q-simplices. Relevant terms such as tangent microbundle, fiberwise tangent microbundle, stably framed family of manifolds, and space of stably framed n-manifolds are taken into account. The chapter also describes the spaces of thickenings and how to straighten the thickenings.Less

This chapter reduces the proof of the manifold part of the stable parametrized *h*-cobordism theorem to a result about spaces of stably framed manifolds. Here Δsuperscript *q* denotes the standard affine *q*-simplex. All polyhedra will be compact, and all manifolds considered will be compact PL manifolds. The chapter begins with a discussion of spaces of PL manifolds. It defines a space of manifolds as a simplicial set, with families of manifolds parametrized by Δsuperscript *q* as the *q*-simplices. Relevant terms such as tangent microbundle, fiberwise tangent microbundle, stably framed family of manifolds, and space of stably framed *n*-manifolds are taken into account. The chapter also describes the spaces of thickenings and how to straighten the thickenings.