ExpandNumerator[expr] expands out products and powers that appear in the numerator of expr.
InverseJacobiCS[v, m] gives the inverse Jacobi elliptic function cs -1 (v \[VerticalSeparator] m).
InverseJacobiDS[v, m] gives the inverse Jacobi elliptic function ds -1 (v \[VerticalSeparator] m).
InverseJacobiSC[v, m] gives the inverse Jacobi elliptic function sc -1 (v \[VerticalSeparator] m).
InverseJacobiSD[v, m] gives the inverse Jacobi elliptic function sd -1 (v \[VerticalSeparator] m).
AiryBiZero[k] represents the k\[Null]^th zero of the Airy function Bi(x).AiryBiZero[k, x_0] represents the k\[Null]^th zero less than x_0.
InverseBetaRegularized[s, a, b] gives the inverse of the regularized incomplete beta function.
InverseJacobiDC[v, m] gives the inverse Jacobi elliptic function dc -1 (v \[VerticalSeparator] m).
A foundational idea in Mathematica is that all expressions—whatever they may represent—ultimately have a uniform tree-like structure.
FunctionSpace is an option for FindSequenceFunction and related functions that specifies the space of functions to consider for representations.