Author: Tony Werten
Date: 00:54:40 03/03/05
Go up one level in this thread
On March 02, 2005 at 20:37:35, Russell Reagan wrote: >On March 02, 2005 at 19:13:38, Matthew Hull wrote: > >>On March 02, 2005 at 18:59:18, Axel Schumacher wrote: > >>>Hi all, >>>I have two question regarding the storage requirements for information; I hope >>>somebody can help me with answering them. Please excuse if my questions are >>>stupid. > >>>1. For each data-point (e.g. let's say the position of a pawn on the chessboard) >>>one requires 1 bit (either 0 or 1). Right? However, the information does not >>>include where the pawn is located. So, how much data has to be stored to >>>describe e.g. the position of a pawn? > > >>In bit-board programs, all paws of a color with their locations can be stored in >>in one 64 bit word. Analysis on the pawn struction can be done with bit masks >>using a single instruction on a 64 bit machine or two instructions on 32 bit (in >>principle). > > >I think the point he is making is that each 64-bit value (bitboard) is just >data, and for it to have meaning it has to be considered under some >interpretation. For instance, my chess program might consider bitboards under >the interpretation that bit position 0 (the least significant bit position) is >a1, bit position 7 is h1, and bit position 63 is h8. Another person might >consider bitboards using a different interpretation. Maybe bit position 0 is a8, >bit position 7 is h8, and bit position 63 is h1. If I give you a 64-bit value >with a single 1-bit, you can't tell me what square the piece is on, or what kind >of piece it is, or what color it is, and so on. I would have to include more >data for the bitboard to have meaning. > >Data compression is a similar situation. If I want to send you a big file, I >will use some program like WinZip to compress it before I send it, but I assume >that you have some program that can decompress it. Let's say that I created my >own compression program that could compress the same file to only 10% the size >of the .zip file that WinZip produced. Now I send you this file. Can you do >anything with it? Probably not, because you need my decompression software to >interpret the meaning of the data I sent you. The data may be compressed far >better, but it has no meaning without knowledge of the method to decompress it. >So the total size of the data, if it is going to have meaning, is the size of >the compressed data plus the size of the program to decompress it. If the >decompression program is a perl script, then the size of the "meaningful data" >is the size of the data, plus the size of the perl script, plus the size of the >perl interpreter. If you want to be really picky, you may even include the size >of the operating system, if that is required to run the perl interpreter. Or >maybe the "meaningful data" would be compressed the smallest using a Forth >interpreter written in x86 machine code, plus a Forth program, plus the data. >But then you need an x86 computer. If there is no intelligent human to interpret >the meaning of the data, does it still have meaning? Probably not, so we need an >intelligent human also. The computer can't run without electricity of course... >:) > >As you can see, the philosophical and theoretical aspects of his question can >get pretty deep. Consider this question: How much space is required to store a >bitboard? It could be as small as "64-bits", or it could be as large as "the >space required to store 64-bits, a computer program to interpret those 64-bits, >a computer to run the program, an intelligent human to interpret the meaning of >the computer's output, and a source of electricity to run the computer." Nice. How much storagespace would 1 human genome take ? x bits + 1 human with y genomes :) Reminds me of "what does Gnu stand for ?" cheers, Tony PS forgive me if the term genome is used incorrect. I haven't got a clue what it is.
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