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A Symbolic Analysis of Relay and Switching Circuits

A Symbolic Analysis of Relay and Switching Circuits

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13<br />

By 129, f<br />

1s equal to the sum <strong>of</strong> t'he produ cts formed<br />

by permuting primes on the terms <strong>of</strong> X X 1 2<br />

••••Xn in all<br />

Possi ble ways <strong>and</strong> giVing each product a coefficient<br />

equal to the value <strong>of</strong> the fU.nction when that product<br />

is 1. Similarly for 12b.<br />

As an application <strong>of</strong> the series expansion it<br />

should be noted that if we wish to find a<br />

circuit<br />

representing any gi van function we<br />

can always exp<strong>and</strong><br />

the function by atther lOa or lOb in such a way that<br />

any given variable appears at most twice, once as a<br />

make contact <strong>and</strong> once 8S 8 break contact. This is<br />

shown in Fi fl;. 4:.<br />

x,<br />

={<br />

x' 1<br />

Fig. ~<br />

Similarly by 11 any other variable need apJEsr no more<br />

than ~<br />

times (two make <strong>and</strong> two break contacts) etc.<br />

,<br />

A generalization <strong>of</strong> De Morgans theorem is<br />

represented symbolically in the following equation:<br />

13. [r(Xl,x21 •••~I + ,.)]1. = f(Xi'X~ ••••Xri'·,+)<br />

By this we mean that the negative <strong>of</strong> any function may

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