A reduction is an arrangement or transcription of an existing score, such as for a symphony or opera, in which complexity has been reduced in order to make analysis, practice or performance easier or clearer. This is accomplished through a decrease in the number of parts so that the work can be be performed by a single instrument (typically a solo piano or organ), by a smaller orchestra, or by a chamber ensemble, while maintaining the melodies, harmonies, bass notes and rhythms of the original to the extent possible.