Maximize question

• To: mathgroup at smc.vnet.net
• Subject: [mg101732] Maximize question
• From: Dana DeLouis <dana.del at gmail.com>
• Date: Wed, 15 Jul 2009 07:12:05 -0400 (EDT)

```Hi.   I found a solution to a Maximum problem by accident and wondered
I'm using v7, but it's the same in v6.

equ = 2^x + 3^y;

I didn't think an upper limit would be required because it's a Max
problem.  It's returned unevaluated...

Maximize[{equ, equ <= 2500, 1 <= x, 1 <= y}, {x, y}, Integers]

<< Unevaluated >>

An upper limit of 1000 is given, but it's still returns unevaluated....

Maximize[{equ, equ <= 2500, 1 <= x <= 1000, 1 <= y <= 1000}, {x, y},
Integers]

<< Unevaluated >>

An upper limit of 100 is accidently given, and I get a solution.

Maximize[{equ, equ <= 2500, 1 <= x <= 100, 1 <= y <= 100}, {x, y},
Integers]

{2443, {x -> 8, y -> 7}}

I can't find anything in the documentation that would suggest a
tighter bounds on the equation in order to evaluate the problem.
Does anyone have any thoughts, or references?