1207.3518 (Sylvain Golenia et al.)

The problem of deficiency indices adjacency matrices on locally finite
graphs    [PDF]

Sylvain Golenia, Christoph Schumacher

In this note we answer negatively to our conjecture concerning the deficiency indices. More precisely, given any non-negative integer $n$, there is locally finite graph on which the adjency matrix has deficiency indices $(n,n)$.

View original: http://arxiv.org/abs/1207.3518