  We investigate the relation between the girth and the guaranteed error
correction capability of $\gamma$-left regular LDPC codes when decoded using
the bit flipping (serial and parallel) algorithms. A lower bound on the number
of variable nodes which expand by a factor of at least $3 \gamma/4$ is found
based on the Moore bound. An upper bound on the guaranteed correction
capability is established by studying the sizes of smallest possible trapping
sets.
