Vladimir Olgerdovich was a son of which ruler of medieval Lithuania?
Algirdas Algirdas (Belarusian: Альгерд , Russian: Ольгерд , Polish: "Olgierd" ;  1296  – May 1377) was a ruler of medieval Lithuania. He ruled the Lithuanians and Ruthenians from 1345 to 1377. With the help of his brother Kęstutis (who defended the western border of the Duchy) he created an empire stretching from the present Baltic states to the Black Sea and to within fifty miles of Moscow.
Simeon of Moscow Simeon Ivanovich Gordiy (the Proud) (Семён Иванович Гордый in Russian) (7 November 1316 – 27 April 1353) was Prince of Moscow and Grand Prince of Vladimir. Simeon continued his father's policies aimed to increase the power and prestige of his state. Simeon's rule was marked by regular military and political standoffs against the Novgorod Republic and Lithuania. His relationships with neighboring Russian principalities remained peaceful if not passive: Simeon stayed aside from conflicts between subordinate princes. He had recourse to war only when war was unavoidable. A relatively quiet period for Moscow was ended by the Black Death that claimed the lives of Simeon and his sons in 1353.