Author/Authors :
We present a simple bijection between diagonally convex directed (DCD) polyominoes with n diagonals and plane trees with 2n edges in which every vertex has even degree (even trees)، نويسنده , , which specializes to a bijection between parallelogram polyominoes and full binary trees. Next we consider a natural definition of symmetry for DCD-polyominoes، نويسنده , , even trees، نويسنده , , ternary trees، نويسنده , , and non-crossing trees، نويسنده , , arbres pairs، نويسنده , , arbres ternaires et arbres sans croisement، نويسنده , , et on prouve que le nombre dʹobjets symétriques dʹune taille donnée est le même dans les quatre cas.، نويسنده ,
Keywords :
Ternary trees , Non-crossing trees , Diagonally convex directed polyominoes , Even trees
