sentences:  His closest collaborator was Juliusz Mieroszewski, who provided the theoretical justification for Polish recognition of the borders with Ukraine, Belarus, and Lithuania (whose future independence he predicted long before it came about).He died in Maisons-Laffitte, Yvelines, Île-de-France, France.In 2006 the Polish Sejm declared the year 2006 as the "Year of Jerzy Giedroyć."