OFFSET
0,3
COMMENTS
This Catalan bijection rotates binary trees right, if possible, otherwise reflects them with the Catalan bijection A057163.
LINKS
A. Karttunen, Gatomorphisms (with the complete Scheme source)
PROG
(Scheme functions implementing this automorphism on list-structures:)
(define (gma082336! s) (cond ((pair? s) (cond ((pair? (car s)) (robr! s)) (else (gma057163! s))))) s)
(define (robr! s) (let ((ex-cdr (cdr s))) (set-cdr! s (caar s)) (set-car! (car s) ex-cdr) (swap! (car s)) (swap! s) s))
(define (swap! s) (let ((ex-car (car s))) (set-car! s (cdr s)) (set-cdr! s ex-car) s))
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Apr 17 2003
STATUS
approved