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MATH211-Exam1
| Term | Definition |
|---|---|
| (definition) universal statement | Says that a certain property is true for all elements in a set. |
| (definition) conditional statement | Says that if one thing is true then some other thing is also true. |
| (definition) existential statement | Says that there is at least one thing for which some property is true. |
| universal statement form | "For all..." |
| conditional statement form | "If..., then..." |
| existential statement uses form | "There exists..." |
| (definition) universal conditional statement | A statement that is both universal and conditional |
| universal conditional statement form | "For all _____(set), if _____(check property), then _____(property to follow)." |
| (definition) universal existential statement | A statement that is universal because its first part says that a certain property is true for all objects of a given type, and it is existential because its second part asserts the existence of something. |
| universal existential statement form | "For all _____(set), there is _____(property/object specific)." |
| (definition) existential universal statement | A statement that is existential because its first part asserts that a certain object exists and is universal because its second part says that the object satisfies a certain property for all things of a certain kind. |
| existential universal statement form | "There exists _____(object in set), such that for all _____(set), _____(property)." |
| (definition) logic | The study of reasoning; it is specifically concerned with whether reasoning is correct. |
| (definition) argument | A sequence of statements aimed at demonstrating the truth of an assertion. |
| conclusion | The assertion at the end. |
| premises | Statements leading to an assertion. |
| (definition) statement/proposition | A sentence that is true or false but not both. The truth value is TRUE if it is true and FALSE if it is false. |
| negation of p | Means "not p" or "it is not that case that p" |
| negation of p denotion | ~p |
| the conjunction of p and q | Means "p and q" |
| the conjunction of p and q denoted | p ∧ q |
| the disjunction of p and q | Means "p or q" |
| the disjunction of p and q denoted | p ∨ q |
| (definition) logical equivalence | Statement forms that have identical truth values for each possible substitution for their statement variables. |
| logical equivalence denoted | P≡Q |
| De Morgan's Laws (a) | ~(p ∧ q) ≡ ~p ∨ ~q |
| De Morgan's Laws (b) | ~(p ∨ q) ≡ ~p ∧ ~q |
| (definition) tautology | A statement that is always true. |
| (definition) contradiction | A statement that is always false. |
| (definition) conditional statements | "if p then q" |
| conditional statements denoted | p --> q (p is the hypothesis, q is the conclusion) |
| (definition) vacuously true | A conditional statement that is true by virtue of the fact that its hypothesis is false. |
| (theorem) p → q ≡∼ p∨q | (theorem) The statement “if p then q” is logically equivalent to “not p or q.” |
| (theorem) ~(p → q) ≡ p ∧ ~q | (theorem) The negation of “if p then q” is logically equivalent to “p and not q”. |
| (definition) contrapositive of p --> q | ~q --> ~p |
| (theorem) p --> q ≡ ~q --> ~p | (theorem) A conditional statement is logically equivalent to its contrapositive. |
| (definition) converse of p --> q | q --> p |
| (definition) inverse of p --> q | ~p --> ~q |
| (definition) "p only if q" means... | "if not q then not p." / "if p then q" |
| Order of operations for logical operators | 1. ~ [negations first] 2. ∧, ∨ [evaluate ∧ ∨ second, parentheses may be needed] 3. -->, <--> [evaluate -> and <--> third, parentheses may be needed] |
| (definition) sufficient condition | If r and s are statements: r is a sufficient condition for s means “if r then s.” r is a necessary condition for s means “if not r then not s” or “if s then r.” |
| (definition) syllogism | An argument form with two premises and a conclusion. |
| modus ponens | p-->q p ∴q |
| modus tollens | p-->q ~q ∴~p |
| rule of inference | A form of argument that is valid. |
| generalization | A valid argument form. p ∴ p∨q q ∴ p∨q |
| specialization | A valid argument form. |
| elimination | p ∨ q ~q ∴ p p ∨ q ~p ∴ q |
| transitivity | p --> q q --> r ∴ p --> r |
| Proof by Division into Cases | p ∨ q p --> r q --> r ∴ r |
| Contradiction Rule | If you can show that the assumption that statement p is false leads logically to a contradiction, then you can conclude that p is true. ~p --> c ∴ p |
| (definition) fallacy | An error in reasoning that results in an invalid argument. |
| converse error | An invalid argument form. p --> q q ∴ p |
| inverse error | An invalid argument form p-->q ~p ∴ ~q |
| (definition) predicate | A sentence that contains a finite number of variables and becomes a statement when specific values are substituted for the variables. |
| (definition) domain | The set of all values that may be substituted in place of the predicate variable |
| Method of Exhaustion | When a domain is finite, a technique for showing that a universal statement is true. |
| (definition) existential statement | A statement of the form “There is an x in the domain such that Q(x)." It is defined to be true if, and only if, Q(x) is true for at least one x in D. It is false if, and only if, Q(x) is false for all x in D. |
| universal conditional statement | "For all of x, if P(x) then Q(x)." |
| (theorem) Negation of a Universal Statement | "For all x in D, Q(x) is true" to "There exists an x in D such that Q(x) is not true." |
| (theorem) Negation of an Existential Statement | "There exists an x in D such that Q(x) is true." to "For all x in D, Q(x) is false." |
| (theorem) Negation of a Universal Conditional Statement | "For all of x, if P(x) then Q(x)." to "There exists an x such that P(x) and ~Q(x)." |
| Sufficient condition for "For all of x, if r(x) then s(x)." | "For all of x in r(x)." |
| Necessary condition for " ~if r(x) then ~s(x)." | "For all of x in r(x)." |
| Only if for "~s(x) then ~r(x)." | "For all of x in r(x)." |
| Rule of Universal Instantiation | If some property is true of everything in a domain, then it is true of any particular thing in the domain. |
| Universal Modus Ponens | (Universal Instantiation) ∀x, if P(x) then Q(x) [<--major premise] P(a) for a particular a [<-- minor premise] ∴ Q(a) |
| Universal Modus Tollens | ∀x, if P(x) then Q(x) ~ Q(a) for a particular a ∴ ~P(a) |
| Universal Transitivity | ∀x, P(x) --> Q(x) ∀x, Q(x) --> R(x) ∴ ∀x, P(x) --> R(x) |
| Converse Error | ∀x, if P(x) then Q(x) Q(a) for a particular a ∴ P(a) |
| Inverse Error | ∀x, P(x) --> Q(x) ~P(a) for a particular a ∴ ~Q(a) |