Max [a,-inf]

*To*: mathgroup at smc.vnet.net*Subject*: [mg48610] Max [a,-inf]*From*: "Peter Pein" <petsie at arcor.de>*Date*: Mon, 7 Jun 2004 05:33:47 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Hi group, does the following make any sense to you? In[1]:= $Version Out[1]= "4.0 for Microsoft Windows (July 16, 1999)" Correct :-)) In[2]:= Simplify[Max[-Infinity, a], a \[Element] Reals] Out[2]= Max[a, -Infinity] Correct but a would be more simple In[3]:= FullSimplify[%, a > -Infinity] Out[3]= Max[a, -Infinity] Correct, but not simplified In[4]:= Simplify[Max[a, b], a > b] Out[4]= a Perfect! Why does Mathematica not recognise 1.) +-Infinity is not an element of the Reals 2.) assuming a>-Inf should give Max[a,-Inf.]->a but: -Infinity \[Element] Reals False which is true so question #1 reduces to: 1a) why is Max[-Inf., some real number] not some real number? The same mess for Simplify[Max[a,Infinity],a \[Element] Reals], which should give Infinity -- Peter Pein, Berlin to write to me, start the subject with [