Given two finite posets P and P' with the same comparability graph, we
show that if \V(P)\ greater than or equal to 4 and if for all x is an
element of V(P), P - x similar or equal to P' - x, then P similar or
equal to P'. This result leads us to characterize the finite posets P
such that for all x is an element of V(P), P - x similar or equal to P
- x. (C) 1998 Academic Press.