%0 Journal Article %A Andrew Douglas %A Joe Repka %T The GraviGUT Algebra Is not a Subalgebra of $E_8$, but $E_8$ Does Contain an Extended GraviGUT Algebra %J Symmetry, integrability and geometry: methods and applications %D 2014 %V 10 %U http://geodesic.mathdoc.fr/item/SIGMA_2014_10_a71/ %G en %F SIGMA_2014_10_a71