Re: Domain of a function

*To*: mathgroup at smc.vnet.net*Subject*: [mg123260] Re: Domain of a function*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Tue, 29 Nov 2011 07:06:08 -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> <201111281052.FAA19690@smc.vnet.net>

Forgot to mention the obvious: Reduce[Element[x | Sqrt[2 + x], Reals]] x >= -2 Andrzej Kozlowski On 28 Nov 2011, at 11:52, Andrzej Kozlowski wrote: > > 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 >

**References**:**Re: Domain of a function***From:*Tutor <alfred.muehlleitner@gmx.at>

**Re: Domain of a function***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>