Complex sentence: He coauthored a number of papers with Paul Erdős, who claimed him as a student, and is the "P" in G.W. Peck, a pseudonym for a group of six mathematicians that includes Purdy.
Split into simpler sentences: He coauthored a number of papers with Paul Erdős, who regarded him as his own student. He is the "P" in G.W. Peck, a pseudonym for a group of six mathematicians that includes Purdy.