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