A Method for Overlapping and Erasure of Lists

An important property of the Newell-Shaw-Simon
scheme for computer storage of lists is that 
data having multiple occurrences need not be stored
at more than one place in the computer.  That is, 
lists may be "overlapped."  Unfortunately, overlapping
poses a problem for subsequent erasure.  Given 
a list that is no longer needed, it is desired to erase
just those parts that do not overlap other lists. 
 In LISP, McCarthy employs an elegant but inefficient solution
to the problem.  The present paper describes 
a general method which enables efficient erasure.  The
method employs interspersed reference counts to 
describe the extent of the overlapping.

CACM December, 1960

Collins, G. E.

CA601210 JB March 20, 1978  6:33 PM

1024	4	106
1051	4	106
1102	4	106
1132	4	106
1390	4	106
1486	4	106
1549	4	106
1706	4	106
1826	4	106
1878	4	106
378	4	106
2060	4	106
2155	4	106
2168	4	106
2719	4	106
2723	4	106
2838	4	106
2842	4	106
2855	4	106
2879	4	106
3077	4	106
3080	4	106
3106	4	106
627	4	106
106	4	106
106	5	106
106	5	106
106	5	106
1050	5	106
210	5	106
1393	5	106
1549	5	106
2023	5	106
3112	5	106
627	5	106
849	6	106
106	6	106
106	6	106
106	6	106
106	6	106
106	6	106
106	6	106
196	6	106
1051	6	106
1380	6	106
209	6	106
1826	6	106
210	6	106
210	6	106
1878	6	106
296	6	106
1972	6	106
367	6	106
2438	6	106
2723	6	106
2736	6	106
2833	6	106
2838	6	106
406	6	106
627	6	106
627	6	106
731	6	106
731	6	106
731	6	106
753	6	106