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Meaning of SUM

Pronunciation:  sum

 
Computing Dictionary
 
 Definition: 

1. In domain theory, the sum A + B of two domains contains all elements of both domains, modified to indicate which part of the union they come from, plus a new bottom element. There are two constructor functions associated with the sum:

        inA : A -> A+B       inB : B -> A+B
        inA(a) = (0,a)             inB(b) = (1,b)

and a disassembly operation:

        case d of isa

This can be generalised to arbitrary numbers of domains.

See also smash sum, disjoint union.

2. A unix utility to calculate a 16-bit checksum of the data in a file. It also displays the size of the file, either in kilobytes or in 512-byte blocks. The checksum may differ on machines with 16-bit and 32-bit ints.

unix manual page: sum(1).

 

 

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