Osculant
From HandWiki
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). Lessons Introductory to the Modern Higher Algebra (4th ed.). Dublin: Hodges, Figgis, and Co.. https://archive.org/details/salmonalgebra00salmrich.
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