Solvability of the $H^\infty$ algebraic Riccati equation in Banach   algebras
  Let $R$ be a commutative complex unital semisimple Banach algebra with the involution $\cdot ^\star$. Sufficient conditions are given for the existence of a stabilizing solution to the $H^\infty$ Riccati equation when the matricial data has entries from $R$. Applications to spatially distributed systems are discussed. 
Amol Sasane
math.OC cs.SY math.AP math.FA math.RA