In this article, we formulate a best proximity pair theorem for noncyclic
relatively nonexpansive mappings in convex metrc spaces by using a geometric
notion of semi-normal structure. In this way, we generalize a corresponding
result in [W. Takahashi, A convexity in metric space and nonexpansive
mappings, Kodai Math. Sem. Rep. 22 (1970) 142-149]. We also establish a best
proximity pair theorem for pointwise noncyclic contractions in the setting of
convex metric spaces. Our result generalizes a result due to Sankara Raju
Kosuru and Veeramani [G. Sankara Raju Kosuru and P. Veeramani, A note on
existence and convergence of best proximity points for pointwise cyclic
contractions, Numer. Funct. Anal. Optim., 82 (2011) 821-830].