From:

~~~ Subject:

On 01/07/95 at 19:43:27 mreid@ptc.com said:

each configuration is stored with 2 bits of memory and thus the whole

space consumes about 42 megabytes. each configuration is assigned

one of 4 values:

distance is currently unknown

distance = current search depth

distance = current search depth - 1

distance < current search depth - 1

This little table reminded me of something I had meant to say about

storing the whole cube space in about 10^18 cells. In principle,

under the Q turn metric it would be possible for each cell to contain

only one bit by storing (depth mod 4)/2. However, in *building*

the solution I think you would need a value in the cell meaning

essentially "distance is currently unknown". Hence, you would need

at least three separate values and therefore at least two bits.

After the table were complete, it might be possible to reduce the

two bits down to one. Even then, you might want to be able to

identify those small percentage of cells which were empty, in which

case you would need two bits anyway. Under the Q+H metric, you

would need two bits in any case to store (depth mod 3), and the

fourth bit pattern would be available to represent "distance is

currently unknown" or "empty cell" as appropriate.

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Robert G. Bryan (Jerry Bryan) (304) 293-5192 Associate Director, WVNET (304) 293-5540 fax 837 Chestnut Ridge Road BRYAN@WVNVM Morgantown, WV 26505 BRYAN@WVNVM.WVNET.EDU