It seems to me that what Venkata Rayudu Posina <posinavrayudu@gmail.com> describes as a "deviation [with ‘do not’] from rule", viz.,
... do not draw more than one arrow from any dot in the domain ...
need not be seen in such a negative light, but can be seen in the more positive light:
all arrows from a given dot in the domain should be completely identical.
I'm just reformulating the approach that "geometric logic" suggests -- not "there shall be no two different ... " but "any two ... shall be one." Oh, wait: do you think that is saying one wants 2 = 1 ? No, no, far from it. What I am proposing, in too much of a hurry to have been clear enough, is: : Given a dot d in the domain and a pair (u, v) of (not necessarily : distinct) arrows u and v from d, one may reasonably required that : "those two are but one", i.e., that u = v . I hope that helps, Posina :-) . Cheers, -- Fred [For admin and other information see: http://www.mta.ca/~cat-dist/ ]