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Re: Domain of a function

• To: mathgroup at smc.vnet.net
• Subject: [mg123228] Re: Domain of a function
• From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
• Date: Mon, 28 Nov 2011 05:52:21 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <j9b6lb$4sv$1@smc.vnet.net> <j9lpke$lif$1@smc.vnet.net> <201111270914.EAA07275@smc.vnet.net>

On 27 Nov 2011, at 10:14, Tutor wrote:

> Element[x | Sqrt[2 + x], Reals]; what exactly does "|" in this case?

The first argument of Element can be a pattern and the assertions is 
that everything that matches the pattern is real. So what kind things 
match the pattern? For one, x matches it. Also, Sqrt[2+x] matches it and 
nothing more does. In other words, both x and Sqrt[2+x] must be real.


Andrzej Kozlowski

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