To compute nullable symbols, we use the following algorithm:

Nullable $=\{\}$

for $i=1$ to $n$ do

if the rule $i$ is of the form $A$ then

Nullable $=$ Nullable $\{A\}$

Change $=$ true

repeat

change $=$ false

for $i=1$ to $n$ do

if the rule $i$ is of the form $A{A}_1{A}_{2}dots{A}_k$ and

$A_{j}in$ Nullable, $1jk$ then

Nullable $=$ Nullable $\{A\}$

if Nullable changed then

change $=$ true

until change $=$ false

We are given the following rules for a context$-$free grammar whose start symbol is A:

Question: Use the algorithm above to calculate the Nullable set. Write the nullable symbols in the order they are found

by the algorithm.

Answer Format. If $A$ is found to be nullable first, then $B$ is found to be nullable, then $C$ is found to be nullable and

these are the only nullable non$-$terminals, your answer should be:

$\{A,B,C\}$