Combinatorial twists in gl_n Yangians

We introduce the special set-theoretic Yang-Baxter algebra and show that it is a Hopf algebra. The associated universal R-matrix is also obtained via an admissible Drinfel'd twist, making the algebra a quasi-triangular Hopf algebra. The fundamental representation of the universal R-matrix yields the familiar set-theoretic (combinatorial) solutions of the Yang-Baxter equation. We then apply the same Drinfel'd twist to the gl_n Yangian after introducing the augmented Yangian. We show that the augmented Yangian is also a Hopf algebra and we obtain the twisted version of the augmented gl_n Yangian as well as the twisted R-matrix.