“…The proposal of [10] was subsequently explored further. In particular, the spectrum of the two descriptions was matched in [15], see also [16] for an earlier analysis, and the asymptotic symmetry algebra of the higher spin theory was shown to agree with the 't Hooft limit of the Wolf space coset W algebras [17]. While many of the features of this duality mirror precisely what happens for the original bosonic proposal [4] and its N = 2 supersymmetric generalisation [18,19], there is one intriguing difference that was already noticed in [10]: while the quantum W ∞ algebras underlying the bosonic and the N = 2 version exhibit a triality or quadrality relation [20,21], respectively, that explains the identification of the quantisation of the asymptotic symmetry algebra with the dual coset algebra even at finite N , a similar relation does not seem to exist in the large N = 4 case.…”