▁Airport ▁( IC A O ▁code : FS AL ) ▁that ▁cross es ▁the ▁island ▁diag on ally . ▁The ▁air field ▁was ▁renov ated ▁in ▁ 2 0 0 0 , ▁and ▁is ▁now ▁serv iced ▁between ▁two ▁and ▁five ▁times ▁a ▁week ▁with ▁an ▁ID C ▁operated ▁fl ights . ▁ ▁Image ▁gallery ▁ ▁References ▁ ▁External ▁links ▁▁▁ ▁Al phon se ▁Island ▁▁ ▁Official ▁Fish ing ▁Oper ator ▁for ▁Al phon se ▁At oll ▁ ▁Island ▁guide ▁ 1 ▁ ▁Se ych elles ▁Bird ▁Records ▁Committee ▁ ▁Island ▁Conserv ation ▁Society ▁ ▁National ▁Bureau ▁of ▁Statistics ▁ ▁Info ▁on ▁the ▁island ▁▁ 2 0 1 0 ▁S ail ing ▁directions ▁ ▁Category : Is lands ▁of ▁Out er ▁Islands ▁( S ey ch elles ) ▁Category : At oll s ▁of ▁Se ych elles <0x0A> </s> ▁Put ney ▁station ▁may ▁refer ▁to : ▁Put ney ▁Bridge ▁t ube ▁station ▁Put ney ▁railway ▁station ▁East ▁Put ney ▁t ube ▁station <0x0A> </s> ▁In ▁mathematical ▁logic , ▁especially ▁set ▁theory ▁and ▁model ▁theory , ▁the ▁back - and - for th ▁method ▁is ▁a ▁method ▁for ▁showing ▁isomorphism ▁between ▁count ably ▁infinite ▁structures ▁satisfying ▁specified ▁conditions . ▁In ▁particular ▁it ▁can ▁be ▁used ▁to ▁prove ▁that ▁▁ ▁any ▁two ▁count ably ▁infinite ▁dens ely ▁ordered ▁sets ▁( i . e ., ▁linear ly ▁ordered ▁in ▁such ▁a ▁way ▁that ▁between ▁any ▁two ▁members ▁there ▁is ▁another ) ▁without ▁end points ▁are ▁is omorphic . ▁An ▁isomorphism ▁between ▁linear ▁orders ▁is ▁simply ▁a