# Combinatorial algorithms in the presence of random errors - II

In the present study, we consider a computational model similar to the
classical RAM machine, except that each instruction performed by the
machine may fail with probability $q< 1/ 6e.$ The failures are
transient and independent of each other. The definition of this
model (which we call ERRAM) follows a previous work \cite{lp},
where we did not allow for addressing errors.
We show how an arbitrary RAM program may be transformed into an
ERRAM program, working with assigned probability $1- \delta,$ provided
that we know the number $T$ of instructions that are executed by the
original program, or an upper bound to it. One major tool that we use is
redundancy, namely, each operation is repeated a certain number of times,
and each stored value is kept in several copies. We derive upper
bounds on the amount of redundancy that is needed to achieve the desired
confidence. This allows us to bound both the space complexity and the
expected time complexity of the resulting ERRAM program, in terms of
$T$, $\delta$ and $q.$