Exercise · ZW-EQUIVALENCE-CLASS-009 · ★★☆ Intermediate
On \(A=\{a,b,c\}\), the equivalence relation is equality. How many classes are there?
Choose one option.
Show answer
- B. 3
Explanation
With equality, \([a]=\{a\}\), \([b]=\{b\}\) and \([c]=\{c\}\): one class per element. So there are 3 classes.
Review the concept: Equivalence class
Given an equivalence relation \(R\) on \(A\) and an element \(a\in A\), the equivalence class \([a]\) is the set of all \(x\in A\) with \(x\,R\,a\).
\[[a]=\{x\in A : x\,R\,a\}\]
More practice problems: equivalence class
- ZW-EQUIVALENCE-CLASS-001 What is the equivalence class [a]?
- ZW-EQUIVALENCE-CLASS-002 What is the quotient set A/R?
- ZW-EQUIVALENCE-CLASS-003 Does a belong to its own class [a]?
- ZW-EQUIVALENCE-CLASS-004 On \1,2,3,4,5,6\ with the relation «same parity», how many equivalence classes are there?
- ZW-EQUIVALENCE-CLASS-005 If x∈[a], what holds?
- ZW-EQUIVALENCE-CLASS-006 On ℤ, let a R b if a-b is a multiple of 3. What is [0]?
- ZW-EQUIVALENCE-CLASS-007 On ℤ, let a R b if a and b leave the same remainder when divided by 3. How many equivalence classes…
- ZW-EQUIVALENCE-CLASS-008 Let A=\1,2,3,4\ and R an equivalence relation with classes \1,2\ and \3,4\. What is [2]?