Opened 8 years ago

Closed 7 years ago

#13788 closed defect (invalid)

FiniteSetMaps Map Comparison

Reported by: startakovsky Owned by: tbd
Priority: major Milestone: sage-duplicate/invalid/wontfix
Component: algebra Keywords:
Cc: Merged in:
Authors: Reviewers: Travis Scrimshaw
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Description (last modified by startakovsky)

Is there a functional reason why comparing domains of functions we can't wrap them as sets before comparing them? A domain and codomain of a map are sets and ultimately should be compared as such when order doesn't matter.

Please advise.

Change History (4)

comment:1 Changed 8 years ago by startakovsky

  • Description modified (diff)

comment:2 Changed 8 years ago by tscrim

  • Component changed from PLEASE CHANGE to algebra
  • Milestone changed from sage-5.9 to sage-duplicate/invalid/wontfix
  • Status changed from new to needs_review
  • Type changed from PLEASE CHANGE to defect

I believe this would be better asked on sage-devel since it is a question rather than a bug or feature request.

Nevertheless, the biggest problem as I see it is how do you compare infinite enumerated sets, much less uncountable ones. Additionally you can encode additional information into the (co)domain which the function reflects. For example, if I define a map from f: {0, 1, 2} -> {0, 1, 2}, there's no way to tell what kind of map do I want, a set map, or perhaps a field homomorphism (although I think this is encoded more in the class of the morphism)? Furthermore, by using the base objects rather than generic sets, equality comparisons can be done significantly faster (ex. take Z mod 1000, you only need to know the class and n rather than having to do a set comparison [which is at least O(n)]).

Last edited 8 years ago by tscrim (previous) (diff)

comment:3 Changed 8 years ago by ncohen

  • Reviewers set to Travis Scrimshaw
  • Status changed from needs_review to positive_review

comment:4 Changed 7 years ago by jdemeyer

  • Resolution set to invalid
  • Status changed from positive_review to closed
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