PEEKABIT, Computer Offspring of Punched
Card PEEKABOO, for Natural Language Searching

The "peekaboo" idea from punched card information
retrieval methods has been mated with the 
idea of superimposed punching to produce a programming
technique which cuts computer run time in half 
on a test search of 33,000 subject index entries.  A search
program using the device has been operational 
since late 1963.  As an item is entered in the store,
an 18-byte mask is created from the item's meaningful 
words using the inclusive OR operation.  If, at search
time, the logical product (using the AND operation) 
of this mask and a similarly constructed question mask
is not equal to the question mask, then one or 
more question words are not present in the store item.
 An equality is in conclusive; the words of the 
store item must be unpacked and compared with question
words.  The present store is made up of over 600,000 
subject index entries estimated to average 60 characters
each.  Longer texts, such as abstracts, could 
be handled by multiple masks.

CACM September,1968

Hutton, F. C.

peekaboo, superimposed coding, natural language
searching text searching, information compaction, 
computer search technique

3.74

CA680901 JB February 22, 1978  9:38 AM

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