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Specifying sign or domain of a variable

• To: mathgroup at smc.vnet.net
• Subject: [mg31458] Specifying sign or domain of a variable
• From: akronimus at yahoo.de (Andre)
• Date: Wed, 7 Nov 2001 05:29:27 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

Hi,

I want to determine the sign of a complex expression by specifying
only the sign or the domains of the basic variables that appear in the
expression (but not inputting any particular values). Unfortunately I
have not been able to specify a variable as e.g. belonging to the set
of positive reals and then using this information for determining the
sign of an expression involving the variable. Does anybody know how to
define variables as belonging to a specific set or to a domain and how
to use these defintions in evaluating expressions composed of the
basic variables? Thanks a lot for your help.

Andre