Premise: Mandolin . It commonly has four courses of doubled metal strings tuned in unison ( 8 strings ) , although five ( 10 strings ) and six ( 12 strings ) course versions also exist . It is the soprano member of a family that includes the mandola , octave mandolin , mandocello and mandobass . The round-back has a deep bottom , constructed of strips of wood , glued together into a bowl .
Hypothesis: There is only one style of the mandolin.
Label: CONTRADICTION