Every local martingale (Yn) can be represented as a martingale transform (Cn)•(Xn) of some martingale
This is from the following lecture notes https://qmplus.qmul.ac.uk/pluginfile.php/2479408/mod_resource/content/3/L3-2020.pdf Theorem 3.12.
Is this true? I don't see any other math resources that state this fact. Further, I am not sure how to prove this seemingly easy result. I found that this is related to "predictable representation property" in Brownian motion, but I haven't learned that far yet. Can you give me some insight?