Primal graphs with small degrees (Q1174168)

Primal graphs were introduced by \textit{A. K. Dewdney} [Aequationes Math. 4, 326--328 (1970; Zbl 0198.29106)]. It is known that there is a unique set \(\pi\) of primal graphs such that every graph has an edge-decomposition into non-isomorphic elements of \(\pi\) and that the only decomposition of an element of \(\pi\) into non-isomorphic elements of \(\pi\) is the obvious one. The authors show that there exist infinitely many elements of \(\pi\) even among graphs with a relatively simple structure.