Bonjour, Here is a question about composable pasting schemes (CPS). In the omega-category In generated by the n-cube, is it possible to find a kind of "general" formula for the (n-1)-source (target) of the n-morphism corresponding to the interior of In ? I can do mechanical computation in low dimension but I am not able for the moment to imagine a formula for any dimension. In high dimension , computations become very long. For example, using notations of Crans/Johnson/Street etc..., in I2, we have (R(x) means the CPS generated by x, sometimes also denoted by (x)) : s_1(00)=R(-0,0+) (almost the definition in a CPS) and t_0(-0)=s_0(0+)=-+ => s_1(00)=R(-0) o_0 R(0+) (1) because the union is the composition in the framework of CPS. And t_1(00)=R(+0,0-)=R(0-) o_o R(+0) (2). Obvious with a picture. In I3, we have : s_2(000)=R(-00,0+0,00-)=R(-00,0++,-0-,0+0,00-,++0) t_0(-00)=s_0(0++) => R(-00,0++) = R(-00) o_0 R(0++) t_0(-0-)=s_0(0+0) => R(-0-,0+0) = R(-0-) o_0 R(0+0) t_0(00-)=s_0(++0) => R(00-,++0) = R(00-) o_0 R(++0) and t_1(R(-00) o_0 R(0++)) = t_1(-00) o_0 R(0++) (axiom of omegaCat) = (-0-) o_0 (-+0) o_0 (0++) with (2) s_1(R(-0-) o_0 R(0+0)) = R(-0-) o_0 s_1(0+0) (axiom of omegaCat) = (-0-) o_0 (-+0) o_0 (0++) with (1) => R(-00,0++,-0-,0+0) = R(-00,0++) o_1 R(-0-,0+0) and in the same way, we preove that t_1(R(-0-,0+0))=s_1(R(00-,++0)) => s_2(000) =((-00) o_0 (0++)) o_1 ((-0-) o_0 (0+0)) o_1 ((00-) o_0 (++0)) For t_2(000), read the above formula from the right to the left and replace - by +. Almost obvious with a picture. For I4 now : I have found a formula for s_3(0000)... A little bit long and not interesting. For I5 : Too long. More generally, the question is : for a CPS, is there a way to compute the source and target of a R({x}) using only compositions of elements like R({y}) ? Thanks in advance for your help. pg.