Mathematical Inequalities & Applications · Volume 17, Issue 4 Functional equations and sharp weak-type inequalities for the martingale square function 17-110 Pages 1499-1513 DOI 10.7153/mia-17-110 Downloads Short PDF Full PDF PNG Authors Adam Osȩkowski Keywords martingale square function optimal stopping free-boundary problem Subject classes 60G40 60G42 35R35 45G10