hemimetric

hemi- +‎ metric

hemimetric (plural hemimetrics)

1. (mathematics) An abstraction of distance; a function, d, with two arguments that satisfies d(x,x) = 0 and d(x, y) + d(y,z) ≥ d(x,z) (the triangle inequality) for all x,y,z in the domain.
   • 2016, Adish Singla, Sebastian Tschiatschek, Andreas Krause, “Actively Learning Hemimetrics with Applications to Eliciting User Preferences”, in arXiv‎:

     Without exploiting structural constraints of the hemimetric polytope, learning the distances between each pair of items requires ${\displaystyle \Theta (n^{2})}$ queries.