Re: Logical Expression
- To: mathgroup at smc.vnet.net
- Subject: [mg73429] Re: Logical Expression
- From: "dimitris" <dimmechan at yahoo.com>
- Date: Fri, 16 Feb 2007 01:00:21 -0500 (EST)
- References: <er1auu$57j$1@smc.vnet.net>
I am not able to explain this behavior of LogicalExpand. But you can use FullSimplify instead. a == 0 && a != 0 FullSimplify[%] a == 0 && a != 0 False a == 0 && a > 0 FullSimplify[%] a == 0 && a > 0 False Dimitris =CF/=C7 Martin Schoenecker =DD=E3=F1=E1=F8=E5: > Common sense tells me that the statement that "something is equal to > zero, and unequal to zero at the same time" is a false statement: > > In[1]:= a == 0 && a != 0 > Out[1]= a\[Equal]0&&a=E2=89=A00 > > In[2]:= LogicalExpand[%] > Out[2]= False > > The same, in my opinion, applies to "something is equal to zero and > greater than zero at the same time". Why doesn't Mathematica think so, > and how to convince it to evaluate the following? > > In[3]:= a == 0 && a > 0 > Out[3]= a\[Equal]0&&a>0 > > In[4]:= LogicalExpand[%] > Out[4]= a\[Equal]0&&a>0 > > > Thanks in advance, > Martin