<math> <apply><forall/> <bvar><ci>x</ci></bvar> <bvar><ci>y</ci></bvar> <apply><eq/> <apply><real/> <apply><plus/> <ci> x </ci> <apply><times/><imaginaryi/><ci>y</ci></apply> </apply> </apply> <ci> x </ci> </apply> </apply> </math>