1. Describe in English the language defined by the following grammar :

->

-> a | a

-> b | b

-> c | c

2. Consider the following grammar :

-> a c | | b

-> c | c

-> d |

Which of the following sentences are in the language defined by this grammar?

a) abcd

b) acccbd

c) acccbcc

d) acd

e) accc

3. Compute the weakest precondition for each of the sequences of assignment statements and their postconditions :

a) a = 2 * b + 1;

b = a - 3

{ b < 0}

b) a = 3 * ( 2 * b + a );

b = 2 * a - 1

{ b > 5 }

Questions 4, 5 and 6 are based on following Grammar:

begin end

| ; = A | B | C

+

| - |

4. Identify the following: Terminals:

Abstractions:

5. Give the parse tree for

Begin A = B+C; B = C end

6. Is the language ambiguous?