In Tetrabiblos, what does Hyleg mean?
hyleg is the Persian-Arabic term for the planet
Title: Tetrabiblos
Passage: Tetrabiblos (Τετράβιβλος ) 'four books', also known in Greek as Apotelesmatiká (Ἀποτελεσματικά ) "Effects", and in Latin as Quadripartitum "Four Parts", is a text on the philosophy and practice of astrology, written in the 2nd century AD by the Alexandrian scholar Claudius Ptolemy ( AD 90– AD 168).
Title: Mean curvature flow
Passage: In the field of differential geometry in mathematics, mean curvature flow is an example of a geometric flow of hypersurfaces in a Riemannian manifold (for example, smooth surfaces in 3-dimensional Euclidean space).  Intuitively, a family of surfaces evolves under mean curvature flow if the normal component of the velocity of which a point on the surface moves is given by the mean curvature of the surface.  For example, a round sphere evolves under mean curvature flow by shrinking inward uniformly (since the mean curvature vector of a sphere points inward).  Except in special cases, the mean curvature flow develops singularities.
Title: Hyleg
Passage: In Hellenistic astrology, the hyleg is the Persian-Arabic term for the planet with the greatest essential dignity in five important natal chart positions (according to Ptolemy's "Tetrabiblos"):
Hyleg Tetrabiblos