Skip to main content
4 events
when toggle format what by license comment
Mar 10, 2014 at 22:38 comment added Hiro Lee Tanaka So I think the limitation isn't in the versatility of the invariants, but in the computability. Lifting Donaldson invariants to the spectrum level (Manolescu) or Casson invariants to a Floer cochain complex (Atiyah-Floer conjecture) are good examples.
Mar 10, 2014 at 22:37 comment added Hiro Lee Tanaka While that might seem like a limitation, objects of a category are usually better invariants than numbers. For instance, if the target category is chain complexes, you get a number of invariants: Euler characteristic and (more generally) Betti numbers or cohomology groups of the chain complex. If your target is spaces, all of a space's topological invariants become an invariant...
Mar 16, 2013 at 17:45 comment added Peter May Jacob himself is very forthright about the limitations of his Theorem 4.1.24 in his illuminating Remark 4.1.27, which starts out "Theorem 4.1.24 is usually not very satisfying, because it describes a functor ... whose values on closed framed n-manifolds are objects of an (\infty,1) category S, rather than concrete invariants like numbers".
Mar 16, 2013 at 14:25 history answered Dmitri Pavlov CC BY-SA 3.0