Condense: \ac12(\gx+\gy)\ac{1}{2}(\g x + \g y)\ac12(\gx+\gy).
\g\rtxy\g \rt{xy}\g\rtxy
\g(\acx+y2)\g (\ac{x+y}{2})\g(\acx+y2)
\rt\gxy\rt{\g xy}\rt\gxy
0.5\gx+0.5\gy0.5\g x + 0.5\g y0.5\gx+0.5\gy