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Apr 4, 2013 at 11:13 vote accept user31968
Apr 3, 2013 at 16:46 comment added HenrikRüping @CC Thank you comments. I agree with your first comment. However your second comment suggests that your definition of $U\circ V$ is my definition of $V \circ U$. (To avoid this I included my definition of $U\circ V$). I still think this is a counterexample.
Apr 3, 2013 at 16:41 history edited HenrikRüping CC BY-SA 3.0
deleted wrong things
Apr 3, 2013 at 14:14 comment added user31968 And for second part $(100,0.5)\in VoU$ because $(100,0)\in U$ and $(0,0.5)\in V$ but $(100,0.5)\notin \{(x,y)| |y-x|<2 \}\cup (\mathbb{R}\times \{0\})$. So $$V\circ U \ne \{(x,y)| |y-x|<2 \}\cup (\mathbb{R}\times \{0\})$$
Apr 3, 2013 at 14:02 comment added user31968 My tries teached me: $U o W = (W^{-1}oU^{-1})^{-1}=(WoU)^{-1}$ and not $WoU$. too common mistake I made too!
Apr 3, 2013 at 13:32 history answered HenrikRüping CC BY-SA 3.0