\[x = 10864 \land y = 18817\]
\[9 \cdot {x}^{4} - \left(y \cdot y\right) \cdot \left(y \cdot y - 2\right) \]
(FPCore (x y)
 :precision binary64
 (- (* 9.0 (pow x 4.0)) (* (* y y) (- (* y y) 2.0))))
double code(double x, double y) {
	return (9.0 * pow(x, 4.0)) - ((y * y) * ((y * y) - 2.0));
}
real(8) function code(x, y)
    real(8), intent (in) :: x
    real(8), intent (in) :: y
    code = (9.0d0 * (x ** 4.0d0)) - ((y * y) * ((y * y) - 2.0d0))
end function
public static double code(double x, double y) {
	return (9.0 * Math.pow(x, 4.0)) - ((y * y) * ((y * y) - 2.0));
}
def code(x, y):
	return (9.0 * math.pow(x, 4.0)) - ((y * y) * ((y * y) - 2.0))
function code(x, y)
	return Float64(Float64(9.0 * (x ^ 4.0)) - Float64(Float64(y * y) * Float64(Float64(y * y) - 2.0)))
end
function tmp = code(x, y)
	tmp = (9.0 * (x ^ 4.0)) - ((y * y) * ((y * y) - 2.0));
end
code[x_, y_] := N[(N[(9.0 * N[Power[x, 4.0], $MachinePrecision]), $MachinePrecision] - N[(N[(y * y), $MachinePrecision] * N[(N[(y * y), $MachinePrecision] - 2.0), $MachinePrecision]), $MachinePrecision]), $MachinePrecision]
9 \cdot {x}^{4} - \left(y \cdot y\right) \cdot \left(y \cdot y - 2\right)

Reproduce

Please include this information when filing a bug report:

herbie shell --seed 2022203 
(FPCore (x y)
  :name "From Rump in a 1983 paper, rewritten"
  :precision binary64
  :pre (and (== x 10864.0) (== y 18817.0))
  (- (* 9.0 (pow x 4.0)) (* (* y y) (- (* y y) 2.0))))

Backtrace

hash-ref: no value found for key key: '~LC
get-parametric-operator/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/syntax.rkt2180
f336.../match/compiler.rkt54840
expand-parametric/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/sugar.rkt620
(unnamed)/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/rules.rkt1768
generate-rules-for/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/rules.rkt1610
generate-missing-rules/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/rules.rkt1870
(unnamed)/data/pavpan/nightlies/herbie/enumo-rat/src/syntax/rules.rkt2926
get-swaps/data/pavpan/nightlies/herbie/enumo-rat/src/symmetry.rkt60
connected-components/data/pavpan/nightlies/herbie/enumo-rat/src/symmetry.rkt170
run-improve!/data/pavpan/nightlies/herbie/enumo-rat/src/mainloop.rkt2960
(unnamed)/data/pavpan/nightlies/herbie/enumo-rat/src/sandbox.rkt556
(unnamed)/usr/share/racket/pkgs/profile-lib/main.rkt4010
profile-thunk/usr/share/racket/pkgs/profile-lib/main.rkt90
(unnamed)/usr/share/racket/collects/racket/engine.rkt4224