1/14
Vocabulary flashcards covering key concepts from Lecture 01: power sets, relations, and partial orders.
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
Power set
The set of all subsets of a given set.
Subset
A set Y is a subset of X if every element of Y is also an element of X.
P(X) (Power set notation)
The set of all subsets of X.
Cartesian product A × B
The set of all ordered pairs (a, b) with a ∈ A and b ∈ B.
Relation
A relation from A to B is a subset of A × B; if A = B, it is a relation on A.
Reflexive relation
A relation R on A is reflexive if for every a ∈ A, (a, a) ∈ R.
Symmetric relation
A relation R is symmetric if aRb implies bRa (i.e., (b, a) ∈ R).
Antisymmetric relation
A relation R is antisymmetric if whenever aRb and bRa, then a = b.
Transitive relation
A relation R is transitive if aRb and bRc imply aRc.
Partial Order (poset)
A relation that is reflexive, antisymmetric, and transitive.
Equivalence relation
A relation that is reflexive, symmetric, and transitive.
Equivalence class
For an equivalence relation ~ on a non-empty set S and a ∈ S, the equivalence class of a is { x ∈ S | x ~ a }.
Non-empty
Having at least one element.
Comparable
In a POSET, two elements x and y are comparable if x ≤ y or y ≤ x.
POSET (Partially Ordered Set)
A non-empty set with a partial order relation (usually written as ≤).