A representation $\pi$ of an involution algebra $A$ by continuous linear operators on a Hilbert space such that $\pi(x)^*=\pi(x^*)$ for all $x\in A$, where $x^*$ is the image of $x$ under the involution of $A$.
References[edit]
[a1] J. Dixmier, "$C^*$ algebras", North-Holland (1977) (Translated from French)