Truth in inequalities
- To: mathgroup at smc.vnet.net
- Subject: [mg29347] Truth in inequalities
- From: Jack Goldberg <jackgold at math.lsa.umich.edu>
- Date: Thu, 14 Jun 2001 02:27:25 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Hi group, Can someone explain the logic of the following: x < Infinity returns x < Infinity while x - Infinity < 0 returns True I should mention that I am aware of the fact that x - Infinity simplifies automatically to -Infinity which is then compared to 0 and found wanting. The issue I'm raising is why should a CAS that has x-Infinity < 0 return True not also return True for the x < Infinity? One awkwardness of having this difference of behavior can be seen in the example, MyFunction[x_,y_]/;(x<y) := blah and MyFunction[x_,y_]/;(x-y<0) := blah do not do the same thing when, say, y=Infinity. Just curious :-) Jack