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.
Narimantas Narimantas or Narymunt (baptized "Gleb", born in 1277 or just before 1300 (according to Wasilewski 1992) – 2 February 1348) was the second eldest son of Gediminas, Grand Duke of Lithuania. During various periods of his life, he ruled Pinsk and Polatsk. In 1333 he was invited by Novgorod's nobles to rule and protect territories in the north, Ladoga, Oreshek and Korela. He started the tradition of Lithuanian mercenary service north of Novgorod on the Swedish border that lasted until Novgorod's fall to Moscow in 1477.