Lax representations via extensions and deformations of Lie symmetry algebras

The challenging problem in the theory of integrable partial differential equations is to find conditions that are formulated in inherent terms of a PDE under study and ensure existence of a Lax representation. The talk will present the technique for constructing Lax representations via extensions of the contact symmetry algebras of PDEs. Also I will show examples that use deformations of infinite-dimensional Lie algebras for searching new integrable PDEs.