471 ;;Quote: networks of relays and switches used for control and protective circuits for telephone exchanges, industrial motor-control, and other automated tasks

471+;;Quote: analyze and simplify relay networks as equations; equivalent to calculus of propositions; produces minimal, series and parallel networks

472 ;;Quote: use truth tables to prove theorems about hindrances, i.e., open or closed circuits; e.g., associative and distributive laws

473 ;;Quote: X' is the negative of X, i.e., the break contacts of a relay; X+X'=1

474 ;;Quote: perfect analogy between calculus of switching circuits and Boolean logic; Huntington's postulates and De Morgan's theorem

476 ;;Quote: series-parallel circuits equivalent to expressions of addition, multiplication, and negation

476+;;Quote: simplify series-parallel circuits by using Shannon's theorems to reduce the number of letters in the expression

482 ;;Quote: sequential circuits built with XY'=0; Y can operate only if X is operated

483 ;;Quote: a lock-in circuit is X=RX+S; X operates from R closing to S opening

484 ;;Quote: the maximal series-parallel circuits are sum_over_n of X_k and its inverse; O(2^n) elements

490 ;;Quote: how to construct a relay switching circuit from equations of the independent and dependent variables

492 ;;Quote: can use relay circuits for complex mathematical operations; anything using a finite number of steps of 'if', 'or', 'and', etc.; e.g., adding two numbers