4. z
SWITCHING CIRCUITS
β collection of wires and switches connecting two terminals, X
and Y
β A switch may be either open (O or 1) or closed (C or 0)
β An open switch will not permit the current to flow while a
closed switch will permit current to flow
X Y
Single Wire
X p Y
Open Switch (O) , p
X p Y
Closed Switch (O) , p
X p q Y
Series Switch: p ^ q Parallel Switch: p v q
X
p
q
Y
5. z
SWITCHING CIRCUITS
β Two switches are complementary if one switch is open and
the other is closed, and vice versa
β Two switches are equivalent if they have the same electrical
properties concerning the flow and non-flow of current
6. z
TRUTH TABLE FOR SWITCHING CIRCUITS
p q p ^ q p v q p q Series
Circuit
Parallel
Circuit
T T T T C C C C
T F F T or C O O C
F T F T O C O C
F F F F O O O O
7. z
SWITCHING CIRCUITS
β Construct the switching circuits equivalent in each of the
following compound statements by applying the laws of
logical equivalence.
1. [(p ^ r) v (q ^ r)] v ~q
8. z
SWITCHING CIRCUITS
1. [(p ^ r) v (q ^ r)] v ~q
[(p ^ r) v (q ^ r)] v ~q β‘
[(p ^ r) v (q ^ r)] v ~q β‘ [(p v q) v ~q] ^ (r v ~q)
Distributive Law
[(p ^ r) v (q ^ r)] v ~q β‘ [(p v (q v ~q)] ^ (r v ~q)
Associative Law
[(p ^ r) v (q ^ r)] v ~q β‘ [(p v q) ^ r] v ~q
Distributive Law
[(p ^ r) v (q ^ r)] v ~q β‘ [(p v q) ^ r] v ~q
Distributive Law
[(p ^ r) v (q ^ r)] v ~q β‘ [(p v q) v ~q] ^ (r v ~q)
Distributive Law
[(p ^ r) v (q ^ r)] v ~q β‘ [(p v (q v ~q)] ^ (r v ~q)
Associative Law
[(p ^ r) v (q ^ r)] v ~q β‘ [(p v T)] ^ (r v ~q)
Inverse Law
[(p ^ r) v (q ^ r)] v ~q β‘ [(p v T)] ^ (r v ~q)
Inverse Law
[(p ^ r) v (q ^ r)] v ~q β‘ T ^ (r v ~q)
Universal Bound Law
[(p ^ r) v (q ^ r)] v ~q β‘ r v ~q
Identity Law
[(p ^ r) v (q ^ r)] v ~q β‘ r v ~q
Identity Law
18. z
Group Enrichment Exercises
β Construct the switching circuits equivalent in each of the
following compound statements by applying the laws of
logical equivalence.
1. [p v (~p v q) v (p v ~q)] ^ ~q
2. ~(p β q) ^ (p β q)
19. z
Group Enrichment Exercises
1. [p v (~p v q) v (p v ~q)] ^ ~q
[p v (~p v q) v (p v ~q)] ^ ~q β‘[p v (~p v q) v (p v ~q)] ^ ~q β‘[p v (~p v q) v (p v ~q)] ^ ~q β‘ [(p v ~p) v q v (p v ~q)] ^ ~q
Associative Law
[p v (~p v q) v (p v ~q)] ^ ~q β‘ [(p v ~p) v q v (p v ~q)] ^ ~q
Associative Law
[p v (~p v q) v (p v ~q)] ^ ~q β‘ [T v q v (p v ~q)] ^ ~q
Inverse Law
[p v (~p v q) v (p v ~q)] ^ ~q β‘ [T v q v (p v ~q)] ^ ~q
Inverse Law
[p v (~p v q) v (p v ~q)] ^ ~q β‘ [(T v q) v (p v ~q)] ^ ~q
Associative Law
[p v (~p v q) v (p v ~q)] ^ ~q β‘ [(q v T) v (p v ~q)] ^ ~q
Commutative Law
[p v (~p v q) v (p v ~q)] ^ ~q β‘ [T v (p v ~q)] ^ ~q
Universal Bound Law
[p v (~p v q) v (p v ~q)] ^ ~q β‘ [T v (p v ~q)] ^ ~q
Universal Bound Law
[p v (~p v q) v (p v ~q)] ^ ~q β‘ [(p v ~q) v T] ^ ~q
Commutative Law
[p v (~p v q) v (p v ~q)] ^ ~q β‘ T ^ ~q
Universal Bound Law
28. z
Group Enrichment Exercises
2. ~(p β q) ^ (p β q)
~(p β q) ^ (p β q) β‘~(p β q) ^ (p β q) β‘~(p β q) ^ (p β q) β‘ ~(~p v q) ^ (p β q)
Implication Law
~(p β q) ^ (p β q) β‘ ~(~p v q) ^ (p β q)
Implication Law
~(p β q) ^ (p β q) β‘ [~(~p) ^ ~q)] ^ (p β q)
De Morganβs Law
~(p β q) ^ (p β q) β‘ [~(~p) ^ ~q)] ^ (p β q)
De Morganβs Law
~(p β q) ^ (p β q) β‘ (p ^ ~q) ^ (p β q)
Double Negation Law
~(p β q) ^ (p β q) β‘ (p ^ ~q) ^ (p β q)
Double Negation Law
~(p β q) ^ (p β q) β‘ (p ^ ~q) ^ [(~p v q) ^ (p v ~q)]
Equivalence Law
~(p β q) ^ (p β q) β‘ (p ^ ~q) ^ (p v ~q) ^ (~p v q)
Commutative Law
~(p β q) ^ (p β q) β‘ (p ^ ~q) ^ (p v ~q) ^ (~p v q)
Commutative Law
~(p β q) ^ (p β q) β‘ [(p ^ ~q) ^ (p v ~q)] ^ (~p v q)
Commutative Law
~(p β q) ^ (p β q) β‘ {(p ^ [~q ^ (p v ~q)]} ^ (~p v q)
Associative Law
~(p β q) ^ (p β q) β‘ {(p ^ [~q ^ (p v ~q)]} ^ (~p v q)
Associative Law
29. z
Group Enrichment Exercises
2. ~(p β q) ^ (p β q)
~(p β q) ^ (p β q) β‘ {(p ^ [~q ^ (~q v p)]} ^ (~p v q)
Commutative Law
~(p β q) ^ (p β q) β‘ {(p ^ [~q ^ (~q v p)]} ^ (~p v q)
Commutative Law
~(p β q) ^ (p β q) β‘ (p ^ ~q) ^ (~p v q)
Absorption Law
~(p β q) ^ (p β q) β‘ (p ^ ~q) ^ (~p v q)
Absorption Law
~(p β q) ^ (p β q) β‘ p ^ [~q ^ (~p v q)]
Associative Law
~(p β q) ^ (p β q) β‘ p ^ [(~q ^ ~p) v (~q ^ q)]
Distributive Law
~(p β q) ^ (p β q) β‘ p ^ [(~q ^ ~p) v (~q ^ q)]
Distributive Law
~(p β q) ^ (p β q) β‘ p ^ [(~q ^ ~p) v (q ^ ~q)]
Commutative Law
~(p β q) ^ (p β q) β‘ p ^ [(~q ^ ~p) v F]
Inverse Law
~(p β q) ^ (p β q) β‘ p ^ (~q ^ ~p)
Identity Law
~(p β q) ^ (p β q) β‘ p ^ (~q ^ ~p)
Identity Law
~(p β q) ^ (p β q) β‘ p ^ [(~q ^ ~p) v F]
Inverse Law
30. z
Group Enrichment Exercises
2. ~(p β q) ^ (p β q)
~(p β q) ^ (p β q) β‘ p ^ (~p ^ ~q )
Commutative Law
~(p β q) ^ (p β q) β‘ p ^ (~p ^ ~q )
Commutative Law
~(p β q) ^ (p β q) β‘ (p ^ ~p) ^ ~q
Associate Law
~(p β q) ^ (p β q) β‘ F ^ ~q
Inverse Law
~(p β q) ^ (p β q) β‘ ~q ^ F
Commutative Law
~(p β q) ^ (p β q) β‘ F
Universal Bound Law
31. z
Group Enrichment Exercises
(p ^ ~q) ^ (p v ~q) ^ (~p v q)
X
Applying the Laws of Equivalence to
~(p β q) ^ (p β q) β‘ (p ^ ~q) ^ (~p v q) ^ (p v ~q)
p ~q
32. z
Group Enrichment Exercises
(p ^ ~q) ^ (p v ~q) ^ (~p v q)
X
Applying the Laws of Equivalence to
~(p β q) ^ (p β q) β‘ (p ^ ~q) ^ (~p v q) ^ (p v ~q)
p ~q
p
~q
33. z
Group Enrichment Exercises
(p ^ ~q) ^ (p v ~q) ^ (~p v q)
X
Applying the Laws of Equivalence to
~(p β q) ^ (p β q) β‘ (p ^ ~q) ^ (~p v q) ^ (p v ~q)
p ~q
p
~q
34. z
Group Enrichment Exercises
(p ^ ~q) ^ (p v ~q) ^ (~p v q)
X
Applying the Laws of Equivalence to
~(p β q) ^ (p β q) β‘ (p ^ ~q) ^ (~p v q) ^ (p v ~q)
p ~q
p
~q
~p
q
35. z
Group Enrichment Exercises
(p ^ ~q) ^ (p v ~q) ^ (~p v q)
X
Applying the Laws of Equivalence to
~(p β q) ^ (p β q) β‘ (p ^ ~q) ^ (~p v q) ^ (p v ~q)
p ~q
p
~q
~p
q
36. z
Group Enrichment Exercises
(p ^ ~q) ^ (p v ~q) ^ (~p v q)
X
Applying the Laws of Equivalence to
~(p β q) ^ (p β q) β‘ (p ^ ~q) ^ (~p v q) ^ (p v ~q)
p ~q
p
~q
~p
q
Y
37. z
SWITCHING CIRCUITS
β’ A number of different patterns of open and closed switches
that will allow the current to flow from X and Y.
β’ In example, using the group enrichment exercises no. 1
β’ The several patterns are illustrated in the following slides.
38. z
SWITCHING CIRCUITS
β’ Case 1: When p = T or closed and q = T or closed
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
39. z
SWITCHING CIRCUITS
β’ Case 1: When p = T or closed and q = T or closed
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
40. z
SWITCHING CIRCUITS
β’ Case 1: When p = T or closed and q = T or closed
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
41. z
SWITCHING CIRCUITS
β’ Case 1: When p = T or closed and q = T or closed
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
42. z
SWITCHING CIRCUITS
β’ Case 1: When p = T or closed and q = T or closed
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
43. z
SWITCHING CIRCUITS
β’ Case 2: When p = T or closed and q = F or open
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
44. z
SWITCHING CIRCUITS
β’ Case 2: When p = T or closed and q = F or open
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
45. z
SWITCHING CIRCUITS
β’ Case 2: When p = T or closed and q = F or open
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
46. z
SWITCHING CIRCUITS
β’ Case 2: When p = T or closed and q = F or open
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
47. z
SWITCHING CIRCUITS
β’ Case 2: When p = T or closed and q = F or open
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
48. z
SWITCHING CIRCUITS
β’ Case 2: When p = T or closed and q = F or open
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
49. z
SWITCHING CIRCUITS
β’ Case 2: When p = T or closed and q = F or open
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
50. z
SWITCHING CIRCUITS
β’ Case 3: When p = F or open and q = T or closed
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
51. z
SWITCHING CIRCUITS
β’ Case 3: When p = F or open and q = T or closed
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
52. z
SWITCHING CIRCUITS
β’ Case 3: When p = F or open and q = T or closed
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
53. z
SWITCHING CIRCUITS
β’ Case 3: When p = F or open and q = T or closed
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
54. z
SWITCHING CIRCUITS
β’ Case 3: When p = F or open and q = T or closed
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
55. z
SWITCHING CIRCUITS
β’ Case 4: When p = F or open and q = F or open
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
56. z
SWITCHING CIRCUITS
β’ Case 4: When p = F or open and q = F or open
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
57. z
SWITCHING CIRCUITS
β’ Case 4: When p = F or open and q = F or open
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
58. z
SWITCHING CIRCUITS
β’ Case 4: When p = F or open and q = F or open
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
59. z
SWITCHING CIRCUITS
β’ Case 4: When p = F or open and q = F or open
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
60. z
SWITCHING CIRCUITS
β’ Case 4: When p = F or open and q = F or open
X
p
Y
[p v (~p v q) v (p v ~q)] ^ ~q
~p
q
p
~q
~q
61. z
Group Reinforcement Activity
Construct the switching circuits in each of the following
equivalent compound statements..
1. (p v q) ^ r ^ q
2. [(p v q) ^ r] ^ q
3. (p v r v ~s) ^ (p v q v r) ^ (p v ~q v s)
84. z
Group Reinforcement Activity
3. (p v r v ~s) ^ (p v q v r) ^ (p v ~q v s)
X
p
v
~s
p
q
r
(p v r v ~s) ^ (p v q v r) ^ (p v ~q v s)
85. z
Group Reinforcement Activity
3. (p v r v ~s) ^ (p v q v r) ^ (p v ~q v s)
X
p
v
~s
p
q
r
p
~q
s
Y
(p v r v ~s) ^ (p v q v r) ^ (p v ~q v s)
86. z
Group Reinforcement Activity
Show the different patterns that will allow the current to flow
from X to Y.
X
p
v
~s
p
q
r
p
~q
s
Y
(p v r v ~s) ^ (p v q v r) ^ (p v ~q v s)
87. z
β’ Levin, O. (2019). Discrete Mathematics: An Open Introduction 3rd Edition. Colorado: School of Mathematics Science
University of Colorado.
β’ Aslam, A. (2016). Proposition in Discrete Mathematics retrieved from https://www.slideshare.net/AdilAslam4/chapter-1-
propositions-in-discrete-mathematics
β’ Operator Precedence retrieved from http://intrologic.stanford.edu/glossary/operator_precedence.html
REFERENCES