"mathematical relationship" is a valid phrase and can be used in written English.
For example, you could say, "We studied the mathematical relationship between the distance and time of a moving object."
That has a mathematical relationship to our posterior distribution.
If a law is a truly exact mathematical relationship, it requires infinite information to specify it.
Saha equation, mathematical relationship between the observed spectra of stars and their temperatures.
Back in 2001 I derived a mathematical relationship between trust and economic performance.
In superstring theory, a mathematical relationship called T duality suggests that one can shrink a circle only so far.
The mathematical relationship of exposure to outcome may be linear, be log linear, or follow some other pattern.
The properties of this force were described above; they are incorporated in the mathematical relationship known as Coulomb's law.
Brewster discovered a simple mathematical relationship between the polarizing angle and the refractive index of the reflective substance.
The mathematical relationship between the graded porosity and compression properties of a FGPS was revealed.
For instance, the October draft said the "heights and proportions of the towers are derived from a mathematical relationship," outlining that with a detailed diagram.
They found a simple mathematical relationship between the size of the weight and the amount of the compression, although the Mylar proved weaker than predicted.
