%0 Journal Article %T Invariant Einstein metrics on flag manifolds with four isotropy summands %A Andreas Arvanitoyeorgos %A Ioannis Chrysikos %J Mathematics %D 2009 %I arXiv %X A generalized flag manifold is a homogeneous space of the form $G/K$, where $K$ is the centralizer of a torus in a compact connected semisimple Lie group $G$. We classify all flag manifolds with four isotropy summands and we study their geometry. We present new $G$-invariant Einstein metrics by solving explicity the Einstein equation. We also examine the isometric problem for these Einstein metrics. %U http://arxiv.org/abs/0904.1690v2