Original sentence: It is known for certain that the wood used included spruce for the top, willow for the internal blocks and linings, and maple for the back, ribs, and neck
Edited sentence: While Stradivari's techniques have long been up for debate and not fully understood by modern craftsmen and scientists, it is known for certain that the wood used included spruce for the top, willow for the internal blocks and linings, and maple for the back, ribs, and neck