1. Recursive Descent Example 1
S  a S b
S  b S a
S  x
All “symbols” starting with uppercase are non-terminals, all other symbols are terminals

2. Recursive Descent Example 2
S  F
F  ID ( ARGS )
ARGS  ARG , ARGS
ARGS  ARG
ARG  ID | IntLit
ID  x | y | z
IntLit  0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9

3. Recursive Descent Example 3
S  if ( ID RelOP ID ) A
A  A A
A  ID = ID
A  ID = IntLit
ID  x | y | z
IntLit  0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
RelOp  < | > | == | != | <= | >=

4. Recursive Descent Example 3a
S  if ( ID RelOP ID ) A
A  B A
A  ε // empty string
B  LID = ID
LID  x | y | z
ID  LID | IntLit
IntLit  0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
RelOp  < | > | == | != | <= | >=