Sometimes systems of ‘spaces’ are used to approximate a space which does not have ‘nice’ properties. This can be a general compact space (as in shape theory, or an object of interest from algebraic geometry such as a scheme or algebraic stack. The use of Čech methods, for instance, allows for the extraction of invariants (and other information) from an approximating pro-space using methods from adapted standard homotopy theory, where standard method cannot be directly applied to the original ‘spatial object’.

Pro-simplicial sets are often called pro-spaces following the tradition in certain schools of homotopy theory of referring to simplicial sets as ‘spaces’.

There are several useful model category structures on categories of pro-spaces. These are described in Isaksen’s paper (listed below).

References

D. C. Isaksen, A model structure on the category of pro-simplicial sets, Trans. Amer. Math. Soc., 353, (2001), 2805–2841

Revised on August 26, 2012 12:30:41
by Tim Porter
(95.147.236.204)