Stabat Mater in F minor, D 383, is a musical setting of the "Stabat Mater" sequence, composed by Franz Schubert in 1816. It is scored for soprano, tenor and bass soloists, SATB choir, 2 flutes, 2 oboes, 2 bassoons, contrabassoon, 2 french horns, 3 trombones, violin I and II, viola, cello and double bass.
Franz Schubert could play the violin
The context only states that the composition consists of a violin, it doesn't say that Franz Schubert could play a violin. He may have got someone else to play it for him. The system likely assumed because the piece contains a violin, Franz Schubert must be able to play it. 
( z1 possible :ARG1 ( z2 play :ARG0 ( z3 person :name ( z4 name :op "Franz" :op "Schubert" ) ) :ARG2 ( z5 violin ) ) )