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.
Lithuanian nobility The Lithuanian nobility was historically a legally privileged class in the Grand Duchy of Lithuania consisting of Lithuanians, from the historical regions of Lithuania Proper and Samogitia, and, following Lithuania's eastern expansion, many Ruthenian noble families ("boyars"). Families were primarily granted privileges for their military service to the Grand Duchy. The Polish-Lithuanian Commonwealth had one of the largest percentages of nobility in Europe, close to 10% of the population, in some regions, like Samogitia, it was closer to 12%.