Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How to verify if a mapping is quotient.

  1. Jun 7, 2012 #1

    SVD

    User Avatar

    Prove or disprove that f is a quotient mapping.
    f:R^3\{(x1,x2,x3):x1=0}--->R^2 defined by

    (x1,x2,x3)|->(x2/x1,x3/x1)
     
  2. jcsd
  3. Jun 7, 2012 #2
    Do you know what the definition of a quotient mapping is?
    What properties should it have?
     
  4. Jun 9, 2012 #3

    Bacle2

    User Avatar
    Science Advisor

    You usually need to have specific topologies defined in your domain and codomain, to test whether a map is a quotient map.
     
  5. Jun 13, 2012 #4
    I would try using directly the definition.

    One direction is definition of continuity, what about the other direction?

    I'm honestly not sure myself, but I would try to show that: at least one partial derivative in at least one coordinate is nonzero → it is localy injective → it is open → it is quotient.





    OT: I'm having trouble coming up with surjective continuous map between euclidean spaces that is not open. Is there some theorem about it? It would mean that every such map is quotient, it seems. If the map was not subjective, it would be easy.

    Another OT, but vaguely related: If a countinuous map between euclidean spaces was open on any open subspace of domain, would it imply all that map would be open? There doesn't seem to be any way of continuously passing from open map on a subspace to a place where it takes open subset to non-open subset. So the OP would need to just check if some nice subspace is open.
     
    Last edited: Jun 13, 2012
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: How to verify if a mapping is quotient.
  1. Quotient map theorem (Replies: 5)

Loading...