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 of vertices delightful if no two of its vertices are connected by an edge, but any vertex not from is connected to at least one vertex from . For which smallest is there necessarily a delightful set of at most vertices?