Exercise · ZW-BINARY-RELATION-005 · ★☆☆ Basic
What is the usual notation for saying that \(a\) is related to \(b\) by \(R\)?
Choose one option.
Show answer
- A. \((a,b)\in R\)
Explanation
A pair \((a,b)\) belongs to \(R\) when \(a\) is related to \(b\). The set \(\{a,b\}\) does not work, because \(\{a,b\}=\{b,a\}\) while \((a,b)\neq(b,a)\).
Review the concept: Binary relation
A set of ordered pairs \((a,b)\) specifying which elements of \(A\) are related to which elements of \(B\).
\[R \subseteq A \times B\]
More practice problems: binary relation
- ZW-BINARY-RELATION-001 What is a binary relation from A to B?
- ZW-BINARY-RELATION-002 How many pairs does A × B have if |A|=2 and |B|=3?
- ZW-BINARY-RELATION-003 If R=\(1,2),(2,3)\, what is the domain of R?
- ZW-BINARY-RELATION-004 If R=\(1,2),(2,3)\, what is the range of R?
- ZW-BINARY-RELATION-006 Let A=\1,2,3\. How many distinct relations are there from A to A?
- ZW-BINARY-RELATION-007 Let A=\1,2,3\ and R=\(a,b)∈ A× A : a≤ b\. Which of these pairs is in A× A but not in R?
- ZW-BINARY-RELATION-008 Let R=\(a,b)∈ ℕ×ℕ : b=a+1\. Which of these pairs belongs to R?
- ZW-BINARY-RELATION-009 A relation R on A is reflexive if (a,a)∈ R for every a∈ A. With A=\1,2,3\, how many reflexive relat…