Re: Reduce in Mathematica 5 vs Mathematica 8 (2nd problem)
- To: mathgroup at smc.vnet.net
- Subject: [mg115357] Re: Reduce in Mathematica 5 vs Mathematica 8 (2nd problem)
- From: Albert Retey <awnl at gmx-topmail.de>
- Date: Sat, 8 Jan 2011 03:41:26 -0500 (EST)
- References: <ig0bsm$sbl$1@smc.vnet.net>
Am 05.01.2011 00:52, schrieb olfa:
> Hi Mathematica Community,
>
> First,wish you happy and successfull new year.
>
> For this 2nd problem in the same subject,I have this system to solve:
>
> Reduce[Not[
> ForAll[{aaP, abP, iP, jP, sP, tP, uP, xP, yP, zP},
> Implies[t == tP && i + x == iP + xP && y == yP &&
> j t + z == jP tP + zP && t x + z == tP xP + zP &&
> Floor[Log[j]/Log[2]] == Floor[Log[jP]/Log[2]] &&
> Floor[Log[x]/Log[2]] == Floor[Log[xP]/Log[2]] && x >= xP,
> t x == tP xP]]]]
>
> in mathematica 5 the output is given in a very short time and is "the
> system cannot be solved with the method available to Reduce" this
> suits me (although I wish it to be the output "True" which is the
> right answer)
>
> in mathematica 8 the kernel still in running indefinitely and this
> does not suit me at all :(
>
> so how to deal with that?
Assuming that you do not now a priory whether Reduce will succeed in a
given time or not, then zou will have to decide on how long you want to
wait for an answer. This will give up after 10 seconds:
TimeConstrained[
Reduce[Not[
ForAll[{aaP, abP, iP, jP, sP, tP, uP, xP, yP, zP},
Implies[t == tP && i + x == iP + xP && y == yP &&
j t + z == jP tP + zP && t x + z == tP xP + zP &&
Floor[Log[j]/Log[2]] == Floor[Log[jP]/Log[2]] &&
Floor[Log[x]/Log[2]] == Floor[Log[xP]/Log[2]] && x >= xP,
t x == tP xP]]]],
10, $Failed
]
hth,
albert