a weaker substitute used to create collections which may not be generated

In diatonic set theory, a bisector divides the octave approximately in half and may be used in place of a generator to derive collections for which structure implies multiplicity is not true such as the ascending melodic minor, harmonic minor, and octatonic scales. Well formed generated collections generators and bisectors coincide, such as in the diatonic collection. The term was introduced by Jay Rahn (1977), who considers any division between one and two thirds as approximately half and who applied the term only the equally spaced collections.

One who, or that which, bisects; esp. (Geom.) a straight line which bisects an angle.

A straight line that divides an object into two equal parts

a line that divides the line segment, angle, or polygon into two equal parts