Plethysm
A group theoretic operation which is useful in the study of complex atomic spectra. A plethysm takes a set of functions of agiven symmetry type 
and forms from them symmetrized products of a given degree 
and other symmetry type 
.A plethysm
satisfies the rules
where
is the coefficient of 
in 
,
where
is the partition of conjugate to , and
where
is the coefficient of in the inner product 
(Wybourne 1970).
References
Littlewood, D. E. ``Polynomial Concomitants and Invariant Matrices.'' J. London Math. Soc. 11, 49-55, 1936. Wybourne, B. G. ``The Plethysm of 
-Functions'' and ``Plethysm and Restricted Groups.'' Chs. 6-7 in Symmetry Principles and Atomic Spectroscopy. New York: Wiley, pp. 49-68, 1970.
- Skew Quadrilateral
- Skew Symmetric Matrix
- Sklar's Theorem
- Skolem-Mahler-Lerch Theorem
- Skolem Paradox
- Skolem Sequence
- Slant Height
- Slice Knot
- Slide Move
- Slide Rule
- Slightly Defective Number
- Slightly Excessive Number
- Slip Knot
- Slope
- Slothouber-Graatsma Puzzle
- Slutzky-Yule Effect
- Sluze Pearls
- Smale-Hirsch Theorem
- Smale Horseshoe Map
- Small Cubicuboctahedron
- Small Ditrigonal Dodecacronic Hexecontahedron
- Small Ditrigonal Dodecicosidodecahedron
- Small Ditrigonal Icosidodecahedron
- Small Dodecacronic Hexecontahedron
- Small Dodecahemicosacron