Complex sentence: Tatu Kolehmainen (21 April 1885--15 June 1967) was a Finnish long-distance runner who competed at the 1912 and 1920 Summer Olympics.
Split into simpler sentences: Tatu Kolehmainen (21 April 1885--15 June 1967) was a Finnish long-distance runner. He competed at the 1912 and 1920 Summer Olympics.