how to show that the following sentence has a denumerable model but not finite model:

for all x there exist y R(x,y) and for all x for all y negation of (R(x,y) and R(y,x) ) and for all x for all y for all z ((R(x,y) and R(y,z) implies R (x,z)).

NOte: I uesd and to mean conjunction ,

R is a binary relation