Hemipyth

Hemipyth refers to the √2.√3 subgroup i.e. intervals that can be constructed by multiplying fractional powers of 2 and 3 where the exponents have a denominator at most 2.

Notable hemipyth intervals include the neutral third √(3/2) = √3/√2, semioctave √2 and the semifourth √(4/3) = 2/√3.