Quote: Boole uses and, or, not, and complement; communtative law and idempotent law

Quotation

Let it further be agreed, that by the combination xy shall be represented that class of things to which the names or descriptions represented by x and y are simultaneously applicable. ... [p. 29] First, it is evident, that ... the order in which two symbols are written is indifferent. ... Hence we have, xy=yx. ... [p.31] if the two symbols have exactly the same signification, their combination expresses no more than either of the symbols take alone would do. In such case we should therefore have xy=x ... [which if we substitute 'x' for 'y', we get xx=x which] assumes the form x^2=x. [Also '-' for not, '1-x' or x-bar for complement, and '+' for or]   Google-1   Google-2

Published before 1923

Related Topics

Topic: logic (84 items)