Author: Uri Blass
Date: 07:12:49 10/03/01
Go up one level in this thread
On October 03, 2001 at 09:42:58, Robert Hyatt wrote: >On October 03, 2001 at 09:12:59, Vincent Diepeveen wrote: > >>On October 02, 2001 at 04:54:13, Bruce Moreland wrote: >> >>>On October 01, 2001 at 00:36:48, Robert Hyatt wrote: >>> >>>>On September 30, 2001 at 14:47:21, Bruce Moreland wrote: >>>> >>>>>On September 29, 2001 at 14:54:03, Robert Hyatt wrote: >>>>> >>>>>>On September 29, 2001 at 10:41:37, Miguel A. Ballicora wrote: >>>>> >>>>>>>Super-linear speedups are "probably" impossible but so far I did not see that >>>>>>>they are "provably" impossible. I would settle with "They are believed to be >>>>>>>impossible". >>>>>>> >>>>>>>Regards, >>>>>>>Miguel >>>>>> >>>>>> >>>>>>They simply _are_ impossible. Unless you believe in perpetual >>>>>>motion, infinite compression, a fire that will burn forever, etc. >>>>> >>>>>Take a human who can move a 200-pound box, but only by scraping it along the >>>>>ground. Compute the time it takes him to move 10 such boxes 100 yards. >>>>> >>>>>Assume that two humans can move a 200-pound box more easily. Can they move a >>>>>200-pound box more than twice as fast as one human? Would this violate laws >>>>>against perpetual motion? Of course not. It is perfectly valid to consider >>>>>working in parallel rather than working serially. The mechanics of the task >>>>>might change, resulting in much increased efficiency -- they can lift the box >>>>>off the ground. >>>> >>>> >>>>I think that after you think about this example, you will see the flaw. >>>>Lifting the box off the ground takes _more_ effort. So the two people are >>>>doing _more_ work in a given period of time than two people pushing two boxes >>>>at the same time. The ancient Egyptions found that dragging was better than >>>>lifting. :) >>>> >>>> >>>> >>>>> >>>>>Two workers cooperating to perform a task, do not *have* to go less than or >>>>>equal to the speed of two workers, each of whom does exactly half of a task that >>>>>can be fairly divided in two. >>>>> >>>>>There exists the opportunity for synergy. >>>>> >>>>>The argument that the above violates the prohibition against perpetual motion is >>>>>fallacious. >>>>> >>>>>bruce >>>> >>>> >>>>Not after you think about it. If two people work and each of them moves 5 >>>>blocks, then they do no more work than the 1 person did moving 10. But they >>>>did it in twice the time. If they _lift_ the block _and_ move it, they are >>>>doing _more_ work per unit of time. They should have moved the blocks >>>>faster one at a time, but they were taking it easy... >>>> >>>> A computer can't do that. >>> >>>You can't possibly be arguing that there is nothing that N (N>1) people can't do >>>in less than 1/N the time that it takes one person. >>> >>>I was trying to find an obvious example. If you don't like that one, I'm sure >>>there is another one. >>> >>>bruce >> >>Obvious example is killermoves. It improves branching factor too. > > >You can't improve branching factor beyond the normal serial search branching >factor. It is truth only if the normal serial search is perfect and cannot be improved. I do not believe in it. Uri
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