Back Writings

1. Erdos--De Bruijn Theorem. This result states that an infinite graph is k-colorable if and only if all its finite subgraphs are k-colorable. This document is a compilation of several proofs other proofs, (July, 2010).
2. Equivalence of three classic statements of set theory: Axiom of Choice, Zorn's Lemma, Well-ordering Theorem. This document is an attempt to present a clear and detailed exposition of the proof. (July, 2010).
3. Havel-Hakimi Theorem deals with the question of existence of a graph with a given degree sequence. (July, 2010)