The L_infty-deformation complex of diagrams of algebras

The deformation complex of an algebra over a colored PROP P is defined in terms of a minimal (or, more generally, cofibrant) model of P. It is shown that it carries the structure of an L_\infty-algebra which induces a graded Lie bracket on cohomology. As an example, the L_\infty-algebra structure on the deformation complex of an associative algebra morphism g, with the underlying cochain complex isomorphic to the Gerstenhaber-Schack complex of g, is constructed. Another example is the deformation complex of a Lie algebra morphism. The last example is the diagram describing two mutually inverse morphisms of vector spaces. Its L_\infty-deformation complex has a nontrivial constant term. Explicit formulas for the L_\infty-operations in the above examples are given. A typical deformation complex of a diagram of algebras is a fully-fledged L_\infty-algebra with nontrivial higher operations.