Complex sentence: Mortimer wrote two best-selling chess books published in London and is the eponym of the Mortimer Defence in the Ruy Lopez and the related Mortimer Trap, and the Mortimer-Frazier Attack in the Evans Gambit.
Split into simpler sentences: Mortimer wrote two best-selling chess books published in London. He is the eponym of the Mortimer Defence in the Ruy Lopez and the related Mortimer Trap, and the Mortimer-Frazier Attack in the Evans Gambit.