Osculant

In mathematics, specifically invariant theory, the osculant or tacinvariant or tact invariant is an invariant of a hypersurface that vanishes if the hypersurface touches itself, or an invariant of several hypersurfaces that osculate, meaning that they have a common point where they meet to unusually high order.

References

  • Salmon, George (1885) [1859]. Lessons Introductory to the Modern Higher Algebra (4th ed.). Dublin: Hodges, Figgis, and Co.