Complex sentence: He (or, less commonly, she) relies on powers of deduction/ratiocination and educated thought to solve crimes, has long been a staple of detective mystery crime fiction, particularly in detective novels and short stories set in Britain in the Golden Age.
Split into simpler sentences: He (or, less commonly, she) relies on powers of deduction/rationalization and educated thought to solve crimes. This has long been a staple of detective mystery crime fiction, particularly in detective novels and short stories set in Britain in the Golden Age.