1. Computer Programming Boolean Logic Trade & Industrial Education
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2. What is Boolean Logic?
Boolean logic is a system for determining the truth of a statement (or expression) based on whether certain variables are true or false. For example: In the statement, “I will go for a walk if it is sunny,” the decision is based on whether it is true that it is ‘sunny.’
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3. Historical Note
George Boole ( ) was an English mathematician who devised a system of symbols and equations to represent logical decisions. Boolean Algebra was not widely used until the invention of computers. Boolean logic expressions are used to design electronic circuits and to represent decision-making in software
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4. How is Boolean Logic used?
A combination of conditions, variables, and operators are used to determine if an expression is True or False.
It can also be used to determine which elements can be members of a given set.
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5. How are these categories different?
Brown-eyed AND Male
Brown-eyed OR Male
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6. Who would be in these groups?
NOT male AND wearing jeans
NOT <16
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7. Like Mathematics, Boolean logic has operators
Mathematic Operators + - x / =
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8. Like Math, Boolean logic has an order of operations
Mathematic Order of Operations is PEMDAS
Parentheses first
Exponents next
Multiplication and Division
Addition and Subtraction
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9. Order of Boolean Operations
1. Parentheses are not operators, but indicate grouping, consider these first. 2. == 3. != 4. not 5. and 6. or is considered last.
p == q
p != q
not p
p and q
p or q
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10. not Tall and Blonde or Rich
Consider the NOT first. Not Tall is short.
Consider the AND next. Not Tall and Blonde, in other words, Short and Blonde.
Consider the OR next.
This person can be either Short and Blonde, or they can be Rich. They can also be Short, Blonde, and Rich.
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11. Order of Operations Parentheses first, then not, then and, then or
Not Tall and Blonde or Rich
Not (Tall and Blonde) or Rich
Not Tall and not Blonde or Rich
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12. Venn Diagrams
Venn Diagrams can be used to visualize Boolean expressions.
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13. Venn Diagram B A A and B Trade & Industrial Education
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14. Where is not A? B A Trade & Industrial Education
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15. Truth Tables
Truth tables are used to evaluate possible combinations of variables and operators.
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16. A OR B A B A or B True False Trade & Industrial Education
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17. A AND B A B A and B True False Trade & Industrial Education
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18. NOT A A not A True False Trade & Industrial Education
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19. not A or B A B not A or B True False Trade & Industrial Education
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20. Check for Understanding
Determining the results of a Boolean expression is known as evaluating it. All Boolean expressions evaluate to either True or False
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21. Evaluate: What would be printed, A or B?
blonde = False
if blonde:
print ‘A'
if not blonde:
print ‘B‘
Answer is B
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22. Evaluate: What would be printed, A or B?
tall = False
female = True
if ( female and tall):
print 'A'
if ( female or tall):
print 'B‘
Answer is B
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23. Evaluate: What would be printed, A or B?
x = False
y = True
if ( x and y):
print ‘A’
if ( not x and y):
print ‘B’
Answer: B
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24. Shade in A and not B B A Trade & Industrial Education
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25. Shade in not A and not B B A Trade & Industrial Education
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26. Will it print? x = True y = False if ( x and not y): print ‘a’
Yes
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27. Will it print? x = True y = False if (not x or y): print ‘a’
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28. With what you know… Can you evaluate a boolean expression?
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