On spectral radius algebras and normal operators Animikh BiswasAlan LambertSrdjan Petrovic 47A1547A6547B15invariant subspacesnormal operatorsspectral radius algebras We associate to each normal operator $N$ an algebra $\mathcal{B}_N$ that contains the commutant of $N$. For a subclass of normal operators we demonstrate that $\mathcal{B}_N$ has a nontrivial invariant subspace. Further, we show that $\mathcal{B}_N$ properly contains the commutant of $N$ so that the invariant subspace result is stronger then the existence of a hyperinvariant subspace. Indiana University Mathematics Journal 2007 text pdf 10.1512/iumj.2007.56.2907 10.1512/iumj.2007.56.2907 en Indiana Univ. Math. J. 56 (2007) 1661 - 1674 state-of-the-art mathematics http://iumj.org/access/