Skip to main content
added 105 characters in body
Source Link
roger123
  • 2.8k
  • 2
  • 29
  • 40

It is easy to prove that a model structure is determined by the following classes of maps (determined = two model structures with the mentioned classes in common are equal).

  • cofibrations and weak equivalences
  • fibrations and weak equivalences

The second statement follows immediately from the first by duality.

What about the following classes of maps/objects (A short argument would be very helpful)?

  1. cofibrations and fibrations
  2. cofibrant objects and weak equivalencescofibrant objects and weak equivalences
  3. cofibrant objects and fibrations
  4. cofibrant objects and fibrant objects

I think each of these classes determine the structure respectively. For the last one I suppose that one has to use framings but I cannot see how to do it.

Edit: Thank you all for the illuminative answers.

  1. true
  2. ?
  3. true
  4. false

It is easy to prove that a model structure is determined by the following classes of maps (determined = two model structures with the mentioned classes in common are equal).

  • cofibrations and weak equivalences
  • fibrations and weak equivalences

The second statement follows immediately from the first by duality.

What about the following classes of maps/objects (A short argument would be very helpful)?

  1. cofibrations and fibrations
  2. cofibrant objects and weak equivalences
  3. cofibrant objects and fibrations
  4. cofibrant objects and fibrant objects

I think each of these classes determine the structure respectively. For the last one I suppose that one has to use framings but I cannot see how to do it.

It is easy to prove that a model structure is determined by the following classes of maps (determined = two model structures with the mentioned classes in common are equal).

  • cofibrations and weak equivalences
  • fibrations and weak equivalences

The second statement follows immediately from the first by duality.

What about the following classes of maps/objects (A short argument would be very helpful)?

  1. cofibrations and fibrations
  2. cofibrant objects and weak equivalences
  3. cofibrant objects and fibrations
  4. cofibrant objects and fibrant objects

I think each of these classes determine the structure respectively. For the last one I suppose that one has to use framings but I cannot see how to do it.

Edit: Thank you all for the illuminative answers.

  1. true
  2. ?
  3. true
  4. false
Source Link
roger123
  • 2.8k
  • 2
  • 29
  • 40

What determines a model structure?

It is easy to prove that a model structure is determined by the following classes of maps (determined = two model structures with the mentioned classes in common are equal).

  • cofibrations and weak equivalences
  • fibrations and weak equivalences

The second statement follows immediately from the first by duality.

What about the following classes of maps/objects (A short argument would be very helpful)?

  1. cofibrations and fibrations
  2. cofibrant objects and weak equivalences
  3. cofibrant objects and fibrations
  4. cofibrant objects and fibrant objects

I think each of these classes determine the structure respectively. For the last one I suppose that one has to use framings but I cannot see how to do it.