MathDB
combi proof without induction

Source: Putnam 1956/B5

November 12, 2019
combinatoricsgraph theoryTuran s theorem

Problem Statement

Show that a graph with 2n points and n2+1n^2 + 1 edges necessarily contains a 3-cycle, but that we can find a graph with 2n points and n2n^2 edges without a 3-cycle.
please prove it without induction .