Chapter 3 Terms Flashcards
Logic
- The science of correct reasoning
- Used within many professions (law, computer programmers, engineers, authors, etc.)
Statement
- A declarative sentence that is either true or false but not both true and false
- You do not have to know for sure that it is true or false, you just know that it must be
Simple Statement
- A statement that conveys a single idea
- It can be true or false
Compound Statement
- A statement that conveys two or more ideas
- Connects simple statements with words and phrases (and, or, if … then, if and only if)
- Truth value depends upon the true or false of each statement and how the statements are connected
p
Connective: –
Symbolic form: p
Statement type: simple
not p
Connective: ~
Symbolic form: ~p
Statement type: negation
p and q
Connective: and
Symbolic form: p( upward arrow )q
Statement type: conjunction
p or q
Connective: or
Symbolic form: p( downward arrow )q
Statement type: disjunction
If p, then q`
Connective: if… ,then
Symbolic form: p -> q
Statement type: conditional
p if and only if q
Connective: if and only if
Symbolic form: p q
Statement type: bi-conditional
What do you know once you know that something is a statement?
- You know that statement is either true or false
Quantifier
- Describes an amount
- Universal
- All, every, none, no
Negation
- Taking a statement and making it false or true
- All x are y = Some x are not y
- No x are y = Some x are y
- Some x are y = No x are y
- Some x are not y = All x are y
Truth Table
- Shows the truth value of a compound statement for all possible truth values of its simple statements
Tautology
- A logic statement that is always true
- To express something by saying it or repeating it in a different way