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Convex compact subset of R^2

  1. Feb 17, 2012 #1
    Let $X$ be a compact and convex subset of $\mathbb{R^2}$

    Let $a^1, a^2 \in X$ such that $a^j = (a^j_1, a^j_2)$, $j=1,2$

    Is $c= \sum_{i=1}^2 \mathbb{I}_{ i=j} a^j_i \in X \quad ?$
  2. jcsd
  3. Feb 18, 2012 #2

    Stephen Tashi

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    Science Advisor

    The '$' won't work as a tag to encapsulate LaTex on this forum. See https://www.physicsforums.com/showthread.php?t=546968

    I don't understand all the symbolism in your question, but using the tags
    Code (Text):
    instead of $, it comes out as:

    Let [itex]X[/itex] be a compact and convex subset of [itex]\mathbb{R^2}[/itex]

    Let [itex]a^1, a^2 \in X[/itex] such that [itex]a^j = (a^j_1, a^j_2)[/itex],[itex]j=1,2[/itex]

    Is [itex]c= \sum_{i=1}^2 \mathbb{I}_{ i=j} a^j_i \in X \quad ?[/itex]
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