Propositions Flashcards
Declarative statements that have a true or false value.
Proposition
Statements contingent upon indefinite values can be propositions.
False
“x = 1” is a proposition.
False
“Pigs can fly” is a proposition
True
Propositions are defined/denoted using the…
Triple bar symbol (≡)
logical operators that join simple propositions into a more complex one
Connectives
¬
Negation
(NOT · · ·)
∧
Conjunction
(· · · AND/BUT/YET · · ·)
∨
Disjunction
(· · · OR · · ·)
→
Implication
(IF · · · , THEN · · ·)
↔
Bi-Conditional
(· · · IF, AND ONLY IF, · · ·)
⊕
Exclusive Or
(· · · (English) OR · · ·)
(NOT · · ·)
negation (¬)
(· · · AND/BUT/YET · · ·)
conjunction (∧)
(· · · OR · · ·)
disjunction (∨)
(IF · · · , THEN · · ·)
implication (→)
(· · · IF, AND ONLY IF, · · ·)
bi-conditional (↔)
(· · · (English) OR · · ·)
exclusive or (⊕)
inverts the truth value of a proposition
negation (¬)
Suppose p ≡ “Birds can sing”, then ¬p ≡
“Birds cannot sing”
combines the truth value of two propositions
conjunctions and disjunctions
A conjunction is only True, when both propositions are…
True
A conjunction is False when at least one connected proposition is…
False
Suppose p ≡ “Birds can sing”, and q ≡ “Travis likes bagels”, then p ∧ q ≡ …
p ∧ q ≡ “Birds can sing, and Travis likes bagels”
Conjunctions give a lot of information when…
True
A disjunction is ___, when at least one connected proposition is true
True
A disjunction is ___when both connected propositions are False
False
Suppose p ≡ “I like bagels”, and q ≡ “My name isn’t Travis”, then p ∨ q ≡ …
“I like bagels, or my name isn’t Travis”
When both statements are True a disjunction is…
True
True ∧ False
False
True ∨ False
True
¬ False
True
False ∧ False
False
___, or conditions (→), are frequently used in mathematics.
Implication
p ≡ “You did your chores” q ≡ “You went to the park” p → q ≡ …
p → q ≡ “If you did your chores, then you went to the park”,
or p → q ≡ “You did your chores, implies you went to the park”
The two parts of an implication
pre-condition and post-condition
A ___ behaves like a contract or promise
Implication or Conditional
A conditional is always True when the post-condition is…
True
A conditional is True when the pre-condition is…
False
In regards to implication, ___ behaves conversely to “if”.
“only if”
The ___ connective is used when implication holds in both directions.
bi-conditional (↔)
p ≡ “I studied”, q ≡ “I passed”, p ↔ q ≡ …
p ↔ q ≡ “I studied, if and only if, I passed.”
requires that both statements are the same truth value
Bi-Conditional (↔)
“English or”
Exclusive Or (⊕)
is True when exactly 1 of the 2 statements are True.
Exclusive Or (⊕)
p ≡ “I studied”, q ≡ “I failed”, p ⊕ q ≡ …
“I studied, or I failed, but not both.”
When both statements are True, then the “exclusive or” is
FALSE
Proposition Order of Operations
- Negation, 2. Conjunction, 3. Disjunction, 4. Implication, 5. Bi-Conditional/Exclusive Or
False ∧ False ∨ True
TRUE
¬ False ∨ True
TRUE
¬ (False ∧ False) ∨ True
TRUE
True ∨ False → False
FALSE
True ∨ True → False
FALSE
True → True ∨ False
TRUE
True ↔ False ⊕ False
TRUE
A conditional can be made ___ by ensuring that the pre-condition is False
TRUE
A conditional can be made True by ensuring that the pre-condition is…
FALSE
Conditionals that have a False pre-condition are vacuously…
TRUE
Conditionals that have a False pre-condition are ___ True.
vacuously
Statements that have identical truth values for every possible
assignment of truth-values for the simple statements are called…
Equivalent
In proofs, ___ can be substituted for each other.
Equivalent Statements
The triple bar (≡) is used to denote…
Equivalent Statements
Statements that have identical truth values for every possible assignment of truth-values for ____ are called Equivalent.
the simple statements
p ∧ p ≡ p
TRUE
q ∨ p ≡ p ∨ q
TRUE
q ∧ p ≡ p
FALSE
q ∨ p ≡ p
FALSE
¬ p ↔ q ≡ q ⊕ p
TRUE
¬ p → q ≡ q ∨ p
TRUE
a statement that results in True for all truth-value assignments of the simple statements
Tautology (T)
A Tautology, T, is a statement that results in ___ for all truth-value assignments of the simple statements.
TRUE
a statement that results in False for all truth-value assignments of the simple statements.
Contradiction (F)
A Contradiction, F, is a statement that results in ___ for all truth-value assignments of the simple statements.
FALSE
A statement is ___ if it is neither a Tautology nor a Contradiction.
Contingent
¬ p is contingent
TRUE
“To Be ∨ ¬ To Be” is a ___ because regardless of whether “To Be” is True or False at least one piece in the “or” is True.
tautology
¬ p → p. Tautology, Contradiction, or Contingent?
Contingent
p → p. Tautology, Contradiction, or Contingent?
Tautology
¬ p ∧ (p ∨ p). Tautology, Contradiction, or Contingent?
Contradiction
¬ p ∧ (q ∨ p). Tautology, Contradiction, or Contingent?
Contingent
p → (p ∨ q). Tautology, Contradiction, or Contingent?
Tautology
In a truth table, the number of combinations/rows is 2^N, where N is…
the number of simple statements
In a truth table, the last column of the simple statments will…
alternate between true and false
In a truth table, the first column top half…
is all true
In a truth table, the first column bottom half…
is all false