Domination Number Calculator

min dominating set γ(G)

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About Domination Number Calculator

A domination number calculator computing γ(G): minimum dominating set. Every vertex is dominated (in S or has neighbor in S). γ(G) ≤ n/2 for connected graphs with n≥2. γ(K_n)=1, γ(C_n)=⌈n/3⌉, γ(P_n)=⌈n/3⌉. Client-side.

Domination Number Calculator Features

  • γ(G) value
  • Ore's bound
  • Common graphs
  • Total domination
  • Independent domination
Domination number γ(G): minimum dominating set S where N[S]=V (every vertex in S or adjacent to S). γ(K_n)=1, γ(C_n)=γ(P_n)=⌈n/3⌉. Ore (1962): γ(G)≤n/2 for connected graphs, n≥2. NP-hard in general.

How to Use

Select graph:

  • γ: Domination number
  • Set: Dominating set
  • Ore: γ ≤ n/2

Domination Variants

Total domination γ_t: every vertex has a neighbor in S (even vertices in S). Independent domination i(G): dominating set that is also independent. Connected domination γ_c: S induces a connected subgraph. Each has different complexity.

Applications

Facility location: place servers to cover all clients. Wireless networks: place access points. Social networks: select influencers to reach everyone. Monitoring: place sensors to observe all locations.

Step-by-Step Instructions

  1. 1Select graph.
  2. 2Compute γ(G).
  3. 3Find dominating set.
  4. 4Check Ore bound.
  5. 5Try variants.

Domination Number Calculator — Frequently Asked Questions

How is γ related to other invariants?+

γ ≤ α (any maximal independent set dominates). γ ≤ τ (any vertex cover dominates). γ ≤ n - Δ (remove a max-degree vertex's non-neighbors). These bounds often give useful estimates.

Is this NP-hard?+

Yes, SET COVER reduces to DOMINATING SET. NP-hard even for planar graphs. But polynomial for: trees (greedy), interval graphs, cographs, and graphs of bounded treewidth. Parameterized complexity: W[2]-complete.

What's Ore's bound?+

γ(G) ≤ n/2 for connected graphs with n≥2 (Ore, 1962). Sharper: γ(G) ≤ n(1+ln(δ+1))/(δ+1) using greedy. For cubic graphs: γ ≤ n/3 (Reed, 1996). These bounds guide algorithm design.

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