01. Under the C language, which issues below require an attribute grammar?  
    A. Preventing the dangling else problem. 
    B. Preventing duplicate identifier names in the same block.
    C. Controlling naming so that a variable name does not begin with a digit. 
    D. Enforcing type checking in parameter passing. 

02. An attribute grammar
    A. adds context-sensitive information to a context-free grammar. 
    B. describes runtime semantics; i.e., the behavior of a running program.
    C. Both statements are true.  

03. In the partial grammar below, assume <string>.Size is an attribute whose
    value is returned by function Size. What type of attribute is Size in
    the context of this production rule? Note that '<-' denotes assignment 
    from right to left.

       <string> ::= <string>[2] x 
       Size(<string>) <- Size(<string>[2]) + 1  

    A. synthesized attribute        
    B. inherited attribute  
    C. both A & B

04. Select the true statement.
    A. Synthesized attributes pass information from child to parent up the 
       parse tree.
    B. The parent node is the head (left-hand side) of a production rule.
    C. both A & B

05. Select the true statements concerning attribute grammars.
    A. The values of intrinsic attributes are assigned before parsing begins.
    B. Inherited attributes are decorated in a bottom-up fashion.
    C. Synthesized attributes carry information up the parse tree.
    D. Intrinic attributes are a type of synthesized attributes.  

  ATTRIBUTE GRAMMAR 1, with semantic rules enclosed in {}.

 1. <assign> -> <var> = <expr>
    Predicate: <var>.type == <expr>.type
 2. <expr> -> <var>[1] + <var>[2]   
    {<expr>.type <- <var[1].type}
    Predicate: <var>[1].type == <var>[2].type
 3. <expr> -> <var>
    {<expr>.type <- <var.type}
 4. <var> -> A | B | C
    {<var>.type <- lookupType(<var>.name)} // lookupType() returns int or real 

06. The predicate in Rule 2 of Attribute Grammar 1 ensures what?
    A. Data types cannot be mixed in expressions.
    B. The type of the left-hand side (lvalue) in an assignment statement must 
       match the type of the right-hand side (rvalue).
    C. both A & B

07. Grammar 1 Rule 2 uses inheritance to pass information from <var>[1].type
    to <expr>.type.

08. The attribute .type in Grammar 1 Rule 4 is assigned a value before parsing 
    begins. 

09. What is true concerning the decorated parse tree for this assignment 
    statement?  A = B + C

                          <assign>
                         /          \
                     <var>   =     <expr>
                    .type=int        .type=?
                      |           /         \ 
                      A      <var>     +    <var>
                            .type=int        .type=?
                               |                |
                               B                C

A. If C is type int the predicate in Grammar 1 Rule 1 will return true. 
B. <expr>.type will be assigned type int by Rule 2.
C. If C is type real the predicate at Rule 2 will return true.
D. This grammar allows compiler coercions. 

ATTRIBUTE GRAMMAR 2 (see text ch 3)
o actual_type: attribute for <var> and <expr> - holds int or real 
o expected_type: attribute for <expr>

Rule 1. <assign> -> <var> =  <expr>
      Semantic rule: <expr>.expected_type <- <var>.actual_type 
Rule 2. <expr> -> <var>[2] + <var>[3]
      Semantic rule: <expr>.actual_type <- 
                   if (<var>[2].actual_type == int) and 
                   (<var>[3].actual_type == int) then int else real      
      Predicate: <expr>.actual_type == <expr>.expected_type
Rule 3. <expr> -> <var>
      Semantic rule: <expr>.actual_type <- <var>.actual_type
      Predicate: <expr>.actual_type == <expr>.expected_type
Rule 4. <var> -> A | B | C
      Semantic rule: <var>.actual_type <- lookup (<var>.string)
Assume these values in the symbol table: int A; real B, real C

10. What is true if you parse B = A with Attribute Grammar 2?
    A. Information is carried from <var> to <expr>.
    B. Information is carried from <expr> to <var>.
    C. Both A & B

11. If you parse C = A with Attribute Grammar 2, what does this semantic rule do?
 
        <expr>.actual_type <- <var>.actual_type  (Rule #3)

    A. <expr>.actual_type is synthesized from <var>.actual_type
    B. <var>.actual_type is synthesized from <expr>.actual_type
    C. <expr>.actual_type is inherited from <var>.actual_type  

12. What is true if you parse the statement below using the symbol table values?
                      C = A

    A. This statement violates the predicate rule that applies to
       <expr> -> <var>[2] + <var>[3]
    B. This statement violates the predicate at Rule 3.
    C. This statement does not violate a predicate rule.

13. What is true about the statement below using the values in the symbol table?
                  B = A + C

    A. This statement violates the predicate at Rule 2.
    B. This statement violates the predicate at Rule 3.
    C. The compiler coerces B to an int in the assignment statement.
    D. The compiler coerces A to a real in the expression A + C.

14. What is true when this predicate is evaluated in Attribute Grammar 2?
      Predicate: <expr>.actual_type == <expr>.expected_type

   A. The value of expected_type has been inherited from the left-hand side of 
      the assignment statement.
   B. The value of expected_type has been synthesized from the right-hand side 
      of the assignment statement.   

15. Prolog is based on a closed world assumption. This means that 
    A. anything you do not know and cannot deduce is false.
    B. unless explicitly known as false you can assume true. 

16. What does this prolog rule mean?
            loves(jack,X) :- rich(X).
    A. jack loves everyone who is rich.
    B. If jack loves you then you are rich.
    C. If you are not rich then Jack does not love you. 

 
17. Which of the following is the correct form of a definite clause? 
    Notation: '^' is AND;   'v' is OR;  '~' is NOT

    A. p ^ q ^ r ^ ... w ^ ~z
    B. ~p v ~q v ~r v ... v ~w v z
    C. ~p ^ ~q ^ ~r ^ ... ^ ~w ^ z  

18. A definite clause without a body is a fact in prolog.

 
19. What does this Prolog rule mean if the universe of discourse is all widgets?

          alsoRelated(X,Y) :- related(Z,X), related(Z,Y).

    A. If every widget that is related to X is also related to Y, then widgets 
       X and Y are alsoRelated.
    B. If there is a widget Z that is related to widget X and also related to
       widget Y, then X and Y are alsoRelated.

20. Which is the correct recursive rule after this rule to define ancestors?
            ancestor(X,Y) :- parent(X,Y).

    A. ancestor(X,Y) :- ancestor(Z,Y), parent(X,Z).
    B. ancestor(X,Y) :- parent(X,Z), ancestor(Z,Y).

21. This BNF grammar
  <cmdlist> ::= <cmd> | <cmdlist>; <cmd>
     is equivalent to this EBNF grammar, where { } denotes 0 or more times.
  <cmdlist> ::= <cmd> | {;<cmdlist>}