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O'Rourke Chapter 7: Search & Intersection in PDF - Computer Science

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Extremal Polytope Queries<br />

Details<br />

source: O’Rourke<br />

Maximum Independent Set is NP-complete,<br />

but greedy heuristic performs well.<br />

Choose vertex of lowest degree, not<br />

adjacent to vertices already chosen.<br />

Algorithm 7.4: : INDEPENDENT SET<br />

Input: : graph G<br />

Output: : <strong>in</strong>dependent set I<br />

I 0<br />

Mark all nodes of G of degree >= 9<br />

while some nodes rema<strong>in</strong> unmarked<br />

do<br />

Choose an unmarked node v<br />

Mark v and all neighbors of v<br />

I I U {v}<br />

spurious<br />

edge<br />

Goal: tetrahedron<br />

triangulate<br />

polytope: lt use convex hll hull<br />

(d) octahedron<br />

(a) Icosahedron<br />

Schlegel<br />

diagram: 5<br />

triangles meet at<br />

each vertex.<br />

There exist at least n/2 vertices of degree<br />

at most 8 (derivation<br />

derivation).<br />

An <strong>in</strong>dependent set of a polytope graph of n vertices<br />

produced by INDEPENDENT SET has size at least n/18 (derivation).

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