Abstract. We review and supplement the recent result by the authors on the reduction of the three dimensional R (3d R) satisfying the tetrahedron equation to the quantum R matrices for the q-oscillator representations of Uq(D2n ) and Uq(C (1) n ). A new formula for the 3d R and a quantum R matrix for n = 1 are presented and a proof of the irreducibility of the tensor product of the q-oscillator representations is detailed.
IntroductionThis paper is a summary and supplement of the recent result [9] by the authors, which is motivated by the earlier works [13,2,11]. The tetrahedron equation (1) [14] is a three dimensional generalization of the Yang-Baxter equation [1]. In [11] a new prescription was proposed to reduce it to the Yang-Baxter equation R 1,2 R 1,3 R 2,3 = R 2,3 R 1,3 R 1,2 by using the special boundary vectors defined by (3) and (10). Applied to a particular solution of the tetrahedron equation (3d L operator [2]), the reduction was shown [11] to give the quantum R matrices for the spin representations [12].In [9] a similar reduction was studied for the distinguished solution of the tetrahedron equation which we call 3d R. The 3d R was obtained as the intertwiner of the quantum coordinate ring A q (sl 3 ) [6], (The original formula on p194 therein contains a misprint.) and was found later also in a different setting [2]. They were shown to coincide and to constitute the solution of the 3d reflection equation in [7]. See [9, App. A] for more detail. The main result of [9] was the identification of the reduction of the 3d R with the quantum R matrices for the quantum affine algebras U q = U q (D