Complex sentence: Vuong and Wyckoff proved a theorem known as the stacking theorem which essentially finds the cover pebbling number for any graph: this theorem was proved at about the same time by Jonas Sjostrand.
Split into simpler sentences: Vuong and Wyckoff proved a theorem known as the stacking theorem which essentially finds the cover pebbling number for any graph. This theorem was proved at about the same time by Jonas Sjostrand.