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ZWMath›Discrete mathematics›Graph theory›Tree›ZW-TREE-003
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AreaCombinatoricsCourseDiscrete mathematicsTopicGraph theory
Proofs and induction4
  • Direct proof
  • Proof by contradiction
  • Mathematical induction
  • Strong induction
Sets and relations4
  • Set operations
  • Inclusion-exclusion principle
  • Partial order relation
  • Hasse diagram
Counting8
  • Multiplication principle
  • Factorial
  • Permutations with repetition
  • Pigeonhole principle
  • Binomial coefficient
  • Binomial theorem
  • Combinations with repetition
  • Permutations and combinations Probability and statistics
Graph theory10
  • Graph
  • Degree of a vertex
  • Path in a graph
  • Connected graph
  • Tree
  • Eulerian cycle
  • Hamiltonian cycle
  • Bipartite graph
  • Graph coloring
  • Planar graph
Recurrences and arithmetic7
  • Recurrence relation
  • Divisibility
  • Greatest common divisor
  • Euclidean algorithm
  • Modular congruence
  • Homogeneous linear recurrence
  • Prime number

Exercise · ZW-TREE-003 · ★☆☆ Basic

The vertices are \(1,\dots,5\). Which of these edge sets forms a tree?

Choose one option.

Show answer
  • A. \(12,23,34,45\)

← Back to the question

Explanation

The path \(12,23,34,45\) is connected and acyclic. The set \(12,23,31,45\) has the cycle \(1,2,3\) and is not connected; \(12,23,34\) leaves vertex 5 isolated; and \(12,23,34,45,51\) is a cycle.

Study Discrete mathematics in ZWMath →

Review the concept: Tree

A tree \(T=(V,E)\) is a connected graph that contains no cycles.

\[|E|=|V|-1\]

More practice problems: tree

  • ZW-TREE-001 How many edges does a tree with 10 vertices have?
  • ZW-TREE-002 A tree has 15 edges. How many vertices does it have?
  • ZW-TREE-004 What is the sum of the vertex degrees of a tree with 7 vertices?
  • ZW-TREE-005 A tree with 7 vertices has one vertex of degree 4, one of degree 3, and the rest are leaves (degree…
  • ZW-TREE-006 One edge is removed from a tree. How many connected components does the resulting graph have?
  • ZW-TREE-007 How many different trees are there on labeled vertices 1,2,3,4?
  • ZW-TREE-008 An acyclic graph has 10 vertices and 3 connected components. How many edges must be added, without…
  • ZW-TREE-009 An edge is added to a tree between two vertices that were not adjacent. The result:

← ZW-TREE-002 ZW-TREE-004 →

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