Complex sentence: On October 21 2005 he was the sole recipient of all five top prizes at the 15th International Frederick Chopin Piano Competition in Warsaw, namely First Prize and polonaise, mazurka, sonata and concerto prizes.
Split into simpler sentences: On October 21 2005 he was the sole recipient of all five first prizes at the 15th International Frederick Chopin Piano Competition in Warsaw. Specifically, he took First Prize and also the polonaise, mazurka, sonata and concerto prizes.