Epimorphisms And Projectivities Of Projective Planes

nary fields we will characterize certain situations where only the projectivities of P' and no further permutations are induced through j. We denote the points (resp. lines) of a projective plane P by lower case (resp. upper case) Latin letters, and write pq for the line joining two distinct points p and q of P. Given a frame (o,u,v,e) of P, following Pickert [9, 1 p.31], we coordinatize the affine 1 Supported in part by the Minerva Foundation, Israel plane P uv with respect to uv as line at infinity and get a Hall ternary field K(o,u,v,e) = (K,T) of P = P(K,T). We identify K with ov\{v} and simply write y for (0,y) and for v. Further let a + b := T(1,a,b), ab := T(a,b,0), K* := K\{0}, and take a -- b, --b, a/c, and c\a to be the elements defined by (a -- b) + b = a, (--b) + b = 0,