Complex sentence: This transform was at the time the subject of a conjecture by Alberto Calderón that Lacey and Christoph Thiele solved in 1996, for which they were awarded the Salem Prize.
Split into simpler sentences: This transform was at the time the subject of a known conjecture, by Alberto Calderón. In 1996, Lacey and Christoph Thiele solved these conjectures, work for which they were awarded the Salem Prize.