A Symbolic Analysis of Relay and Switching Circuits

9
as are the hinderance functions above. Usually t~e two
sUbjects are developed simultaneously from tae Same set
01 postulates, except for the addition in t~e case of
the Cctlculus of Propositions of a postulate e~uivalent
to postulate 4 aoove.
S.V. Huntington (4) gives tne
followin5 set of postulates for symbolic logic:
1. Tne class K contains at least two distinct
elements.
2. If a and b are in tne class K tnen a+ b is
in tl1.e class K.
3- a+bzb+a
4. (a. b) + C = a + (b ... c)
5. a+a:a
6. ab + ab ':: a where ab is defined as (a'+ b '
)'
If we let t~e class K be t~e class consisting of the
two elem~nts
0 and 1, taen tnese postulates follow from
those given on pages 5 and 6. Also postulates 1, 2,
and 3 given tnere can be deduced from Huntington's
postulates.
Aduing 4 and restricting our discussion
to tile CEi.lculus of propos i tions, i t
is evident that a
perf'ect tine.logy exists between tne calculus for switcning
cireuits B.Jlli tIlis br2J1Ch of symbolic loSlc.* The
two interpretctions of t~e symbols are sh:wn in Table 1.
*This 8.nalogy lllay also be seen from a slishtly d.ifferent
viewpoint. Instead of associating Xab directly wltfi the
circuit a-b let Xab represent t~e grooosition tnat the