Simplify the following text for a Grade 8 native English-speaking person.
Original: Chigorin has several chess openings or variations of openings named after him , the two most important being the Chigorin Variation of the Ruy Lopez ( 1 .
Simplified: Chigorin made a number of contributions to the theory of chess openings . The most important were the Chigorin Variation of the Ruy Lopez ( 1 .