Memorise! Flashcards
Truth table Implication
A | B | Output
0 0 1
0 1 1
1 0 0
1 1 1
Truth table bi-implication
A | B | Output
0 0 1
0 1 0
1 0 0
1 1 1
Simplification of Implication
a => b = not(a)Vb
Simplification of Bi-Implication
a <=> b = (a=>b) n (b=>a)
Tautology
Proposition that is always true
Contradiction
Proposition that is always false
Contingency
Proposition that is not a tautology or contradiction
Definition of Consequence
Q is a logical consequence of D if for every “output value”, if D evaluates to True, then Q evaluates to True
D|= Q
Definition of Comparable
If Q is a logical consequence of P, or P is a logical consequence of Q, then they are comparable
Definition of Strongness & Weakness
False is strongest, True is weakest
P is a logical consequence of Q = P is stronger then Q, Q is weaker then P
De Morgan’s law for Quantifiers
not Ax[P:Q] = Ex[P: not q]
not Ex[P:Q] = Ax[P:not q]
Introduction and Elimination Rules for Conjunction, Disjunction, Implication, Bi-implication, Negation, Contradiction, Double Negation, Contraposition, Case Distinction
write it!
Introduction and Elimination Rules for Universal and Existentisal Quantification
5 in total!
(universal intro &elim)
(existensial intro &elim)
(normal existensial intro)
Property and Definition Rules
Property = Intro, Definition = Elim
Property and Definition Rules for =, n, u, complement, difference, empty set, subset, Powerset,
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Ordered Pair
Two elements with fixed ordering (a,b), a is the first and b is the second
Property of Ordered Pair
(a,b) = (a’,b’)
logically equivalent to
(a=a’) n (b=b’)
Cartesian Product
The set of all ordered pairs (a,b) with a exists in A and b exists in B
Property of Cartesian Product
(a,b) exists in AxB
logically equivalent to
a exists in A n b exists in B
Definition of a Relation
A set of ordered pairs
Cartesian Graph
A graph that corresponds to an ordered pair that shows which are related
Arrow Graph
Draw it!
Reflexive Property Definition
Ax[x in A: xRx]
Symmetry Property Definition
Ax,y[x,y in A: xRy => yRx]