?? b2 ....


k[a:(x,x),b:(x,y-x),c:(x,-x),d:(x,x-y),e:(y,y),f:(y,y-2x),g:(y,-y),h:(y,2x-y),j:(y,0)] / ef+gh+j^2, ????

so(m+1,n+1) acting on .... ??? conformal completion of flat signature (m,n) space .... ???? .....

projective light cone in flat (m+1,n+1)-space as ess that conformal completion ?? ....

?? _are/were_ we having some point/line confusion here again ??? .....

?? light cone lives _in_ point space, not in light-ray space ... ?? ....

?? gimbal configuration space = so(3) = rp^3 .... ???? = light-ray space ???

?? axis configuration space = conformal 2+1 space-time .... ???? ....

??? interpret a,b,c,d as giving isometry from s^1 to s^2 .... ????? .... and separate e,f,g,h,j into 2 parts, one giving point of s^1, other giving point of s^2 .... ???? .... evaluation .... ????.....

e-g and f-h ... ???

e+g, f+h, and j .... ?????.....


k l m
n p q

??? ....

?? quaternions .... ??? projective quaternion .... ????? .... ?? conjugation action on imaginary quaternions ... ??? 2d subspace in imaginary quaternions ... ??? ....