MathDB
Delightful sets of vertices

Source: Russian TST 2020, Day 4 P2

March 21, 2023
graph theorycombinatorics

Problem Statement

There are 10,000 vertices in a graph, with at least one edge coming out of each vertex. Call a set SS{} of vertices delightful if no two of its vertices are connected by an edge, but any vertex not from SS{} is connected to at least one vertex from SS{}. For which smallest mm is there necessarily a delightful set of at most mm vertices?