Scattering Number Calculator

fragmentation surplus

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About Scattering Number Calculator

A scattering number calculator computing sc(G) = max over cut sets S of ω(G-S) - |S|. Measures how much fragmentation exceeds separator cost. sc ≤ 0 for Hamiltonian. sc = n-2 for stars. Dual viewpoint to toughness. Client-side.

Scattering Number Calculator Features

  • sc(G)
  • ω-|S|
  • Ham ≤ 0
  • Stars = n-2
  • Common graphs
Scattering number sc(G) = max over cut sets S of ω(G-S) - |S|. If sc ≤ 0: graph might be Hamiltonian. Stars: sc = n-2 (many pieces, small separator). Complete graphs: sc = 2-n. Measures vulnerability from the attacker's perspective.

How to Use

Select graph:

  • sc: Scattering #
  • ω-|S|: Surplus
  • Ham: sc ≤ 0?

Interpretation

sc > 0: attacker can create more fragments than vertices removed. Bad for network resilience! sc ≤ 0: defender always 'wins' — removing k vertices creates at most k pieces. Good for Hamiltonicity.

Extreme Cases

Star K_{1,n-1}: remove center → n-1 pieces, |S|=1, sc = n-2 (very vulnerable). K_n: remove k → 1 piece, sc = max(1-k) = 2-n (very robust). Path P_n: sc = 1 (moderately vulnerable).

Step-by-Step Instructions

  1. 1Select graph.
  2. 2Find max ω-|S|.
  3. 3Check sc ≤ 0?.
  4. 4Compare extremes.
  5. 5Assess vulnerability.

Scattering Number Calculator — Frequently Asked Questions

How does scattering number relate to Hamiltonicity?+

Necessary condition: Hamiltonian → sc ≤ 0. Not sufficient! But combined with other conditions, powerful. sc ≤ 0 means you can't create more pieces than vertices removed.

Why is it the 'dual' of toughness?+

Toughness: min |S|/ω (defender view, ratio). Scattering: max ω-|S| (attacker view, difference). Both measure the same vulnerability from opposite perspectives. sc ≤ 0 ⟺ toughness ≥ 1.

What graphs have sc = 0?+

Cycles: sc = 0 (remove k → k pieces). Threshold for Hamiltonicity. Most 2-connected graphs have sc ≤ 0. Trees (non-stars) typically have sc > 0.

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