Fischer random chess numbering scheme: Difference between revisions

Revision as of 20:15, 21 March 2022

Revision as of 01:34, 22 March 2022

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The methods described below are appropriate for the idn range 0-959. For the idn range 1-960, he recommends conversion by dividing by 960 and working with the remainder. This has the effect of assigning to idn 0 the SP that was at idn 960, and leaving the other idn SP matchups unchanged. If this calculation is applied in the idn range 0-959, nothing is changed.

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For any SP, after skipping over the bishop's, the queen may occupy any one of six possible squares, and they are numbered from left to right (from White's perspective) 0,1,2,3,4,5. The two knights, then, can appear in any of the remaining five squares (skipping over bishops and queen) in 10 ways. These are shown and numbered in the N5N table below.

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|+Scharnagl's N5N Table

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For any SP, after skipping over the bishop's, the queen may occupy any one of six possible squares, and they are numbered from left to right (from White's perspective) 0,1,2,3,4,5. The two knights, then, can appear in any of the remaining five squares (skipping over bishops and queen) in 10 ways. These are shown and numbered in the N5N table below.

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|+Scharnagl's NQ-skeleton Table

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| 1 || NNQ--- || 241 || NN-Q-- || 481 || NN—QNN--Q- || 721 || NN---Q

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| 17 || NQN--- || 257 || N-NQ—NQ-- || 497 || N-N-Q- || 737 || N-N--Q

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| 33 || NQ-N-- || 273 || N-QN—QN-- || 513 || N--NQ- || 753 || N--N-Q

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| 49 || NQ—NNQ--N- || 289 || N-Q-N- || 529 || N--QN- || 769 || N---NQ

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| 65 || NQ---N || 305 || N-Q--N || 545 || N--Q-N || 785 || N---QN

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| 81 || QNN--- || 321 || -NNQ—NNQ-- || 561 || -NN-Q- || 801 || -NN—QNN--Q

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| 97 || QN-N-- || 337 || -NQN—NQN-- || 577 || -N-NQ- || 817 || -N-N-Q

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| 113 || QN—NQN--N- || 353 || -NQ-N- || 593 || -N-QN- || 833 || -N--NQ

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| 129 || QN---N || 369 || -NQ—NNQ--N || 609 || -N-Q-N || 849 || -N--QN

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| 145 || Q-NN—NN-- || 385 || -QNN—QNN-- || 625 || —NNQ--NNQ- || 865 || —NN--NN-Q

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| 161 || Q-N-N- || 401 || -QN-N- || 641 || —NQN--NQN- || 881 || —N--N-NQ

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| 177 || Q-N--N || 417 || -QN—NQN--N || 657 || —NQ--NQ-N || 897 || —N--N-QN

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| 193 || Q--NN- || 433 || -Q-NN- || 673 || —QNN--QNN- || 913 || ---NNQ

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| 209 || Q--N-N || 449 || -Q-N-N || 689 || —QN--QN-N || 929 || ---NQN

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| 225 || Q---NN || 465 || -Q--NN || 705 || —Q--Q-NN || 945 || ---QNN

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