“…C W S C op ! .S#NC/ is not a right Quillen equivalence, between S C op and the closed model category of pointed objects over NC (ie, of retractive simplicial sets over NC ), except for example, when C is a groupoid (see Hollander [38,Theorem 2.7], or Dror, Dwyer and Kan [23] for C D G a group). The closed model structure on .S#NC/ is induced by the usual one of simplicial sets; that is, where a map is a weak equivalence, cofibration or fibration if and only if it is a weak equivalence, cofibration or fibration of simplicial sets, respectively.…”