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Math Help - What does \upharpoonright mean?

  1. #1
    MHF Contributor Drexel28's Avatar
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    What does \upharpoonright mean?

    Hello friends,

    While reading the book Representations of Finite and Compact Groups by Barry Simon I came upon the notation \upharpoonright which he fails to define. From context I would guess it means "restriction" but I can't be sure. For example here's some context


    Let U:G\to V be a representation of G on V and suppose that W\leqslant V is invariant under U. Then, U\upharpoonright W and U\upharpoonright W^{\perp} define representations U_1 and U_2 and U is equivalent to U_1\oplus U_2
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    Yes - that symbol is generally used to restrict a function to a smaller domain.
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    MHF Contributor Drexel28's Avatar
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    Quote Originally Posted by DrSteve View Post
    Yes - that symbol is generally used to restrict a function to a smaller domain.
    Strange, I have ALWAYS (and I've looked through a few books in my time) seen U_{\mid Y}.
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  4. #4
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    I actually use both notations pretty regularly, but I don't remember where and when I learned to use each of them.
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