Hjelmslev's theorem

Meaning

Proper Noun

• a theorem stating that if a set of points $\{P\_i\}$ lying on a line is isometrically mapped to points $\{P\_i\text{'}\}$ on a different line, then the midpoints of the segments $P\_iP\_i\text{'}$ also lie on a line.

Origin

• Named after Johannes Hjelmslev.