Let A be finite relational structure of finite type, and let CSP (A) denote the following decision problem: if I is a given structure of the same type as A, is there a homomorphism from I to A ? To each relational structure A is associated naturally an algebra A whose structure determines the complexity of the associated decision problem. We investigate those finite algebras arising from CSP’s ...

We show that the image of a commutative monotone sequentially complete C∗-algebra, under a sequentially normal morphism, is again a monotone sequentially complete C-algebra, and also a monotone sequentially closed C∗-subalgebra. As a consequence, the image of an algebra of this type, under a sequentially normal representation in a separable Hilbert space, is strongly closed. In the case of a un...