... {1,x,x2,x3,x4,x5,x6}.14.a) Mˆo˜i phˆa`ntu.’cu’a S3l`a mˆo.t ho´an vi.cu’a {1, 2, 3},t´u.cl`amˆo.t song ´anh{1, 2, 3}−→{1, 2, 3}. Ph´ep to´an t´ıch trˆen S3ch´ınh l`a ph´ep ho..p th`anh ´anh xa..C´ac ... (H)] = n.1524.a) V´o.imo.i y ∈ G,tˆo`nta.i duy nhˆa´t x = g−1yg sao cho Cg(x)=y,nˆenCgl`a mˆo.t song ´anh. Ngo`ai ra, Cg(xx)=gxxg−1= gxg−1.gxg−1= Cg(x)Cg(x).Do d¯´o Cgl`a mˆo.ttu..d¯ ˘a’ng ... = (y(mod m),y(mod n)). Do d¯´o f l`a mˆo.td¯o.n ´anh. V`ı|Zmn| = |Zm× Zn| = mn nˆen f l`a mˆo.t song ´anh. Ngo`ai ra,f(x(mod mn)+y(mod mn)) = f (x + y(mod mn))=(x + y(mod m),x+ y(mod n))=(x(mod...