Math: set subtraction

Tutoring math, ideas can always be revisited. The tutor mentions set subtraction.

Set subtraction is different from arithmetic subtraction. If A and B are sets, the operation A-B ignores what’s in B only; it just gives back what’s present in A yet absent in B.

Therefore, if A={M,N,Q} and B={Q,T,X,Z}, A-B is {M,N}. Furthermore, if B={Q,T,X,Z,1,2,3,4,5}, A-B remains {M,N}.

Kind of interesting, eh?

Source:

Connolly, Thomas M. and Carolyn E. Begg. Database Systems. Toronto: Pearson, 2015.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

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