On Friday 20 September 2002 22:42, Torben Schlüntz wrote: > Anyone receiving a TF task could edit the worktodo.ini from > Factor=20.abc.def,59 > to > Factor=20.abc.def,65 > He would receive approx. twice the credit the effort is worth.
Not quite - even allowing for the 1/2^6 effort involved in TF through 59 bits ... through 64 bits the algorithm runs much faster than it does for 65 bits and above. The factor is around 1.6 rather than 2. > Ofcourse nobody would do this, as we are all volunteers! Or could > somebody some day be tempted to raise his rank using this method? Never underestimate what some people may do to rig league tables! > Does GIMPS hold some log for TF's done by which account? If so could > this log please be open? I think the log exists but, since intermediate checkpoints are not logged, it might not show anything. > Would this cheat be trapped later by P-1 or does P-1 trust earlier work > so factors below say 67-bits are not considered? P-1 doesn't care what (if any) TF has been done previously. _Some_ but by no means all "missed" factors would be picked up bt P-1. Note also that some factors may be missed due to genuine "glitches" as opposed to deliberate skipping. > The above questions are _not_ asked because I intend to use the method. > > :-/ I think it would miscredit GIMPS as we trust the results of GIMPS. > > And I would be disappointed if I learned that an LL I did could have > been solved far earlier - and using less effort. Yes - but as TF is primarily designed to reduce LL testing effort, missed factors are an inefficiency rather than a serious problem. Suggestion: TF should report completion of each "bit" to PrimeNet, not just the on completion to the target depth. I don't see how this would require changes to the server, though there would be a (relatively small) increase in load. Suggestion: the TF savefile should be modified to contain an internal consistency check (say the MD5 checksum of the decimal expansion of the current factoring position) so that cheating by editing the savefile, causing "jumping" past a large range of possible factors, would be made a great deal more difficult. Regards Brian Beesley _________________________________________________________________________ Unsubscribe & list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
