?? essentialness of diagonal ..... ????? ....

?? theorem about when classical model category of topos of filteredly cocontinuous set-valued functors on x is equivalent to x as expected to have "at least as many complications" as diaconescu's theorem .... ???? ....

?? diaconescu's theorem for locales ??

?? discussions of essential inclusions between sober spaces in johnstone's or other books maybe ?? ...