# Simultaneity

**Simultaneity**is the property of two events happening at the same time.

- In mathematics, a
**system of equations**or a set of**simultaneous equations**share variables; a solution is a set of variable values for which all these equations are satisfied simultaneously. - In music a
**simultaneity**is more than one complete musical texture occurring at the same time, rather than in succession. This first appeared in the music of Charles Ives, and is common in the music of Conlon Nancarrow, and others. A**pitch simultaneity**is also more than one pitch or pitch class all of which occur at the same time, or simultaneously.*Simultaneity*is a more general term than chord: most chord progressions or harmonic progressions are then simultaneity successions, though not all simultaneity successions are harmonic progressions and not all simultaneities are chords.

## See also

- Equation
- Relativity of simultaneity
- Synchronization
- Musical set theory