Exercise 8, Grammar Development

Complementation and Control

Control: COMPs and XCOMPs

Integrate COMPs and XCOMPs into your grammar. The following sentences should work:

• John promised the cat to eat yoghurt.
• John persuaded the cat to eat yoghurt.
• John wanted to eat yoghurt.
• John wanted the cat to eat yoghurt.
• John thought that the cat ate the yoghurt.

You will need to expand your grammar rules along the lines shown below. Your VP rule will, of course, be more complex than that shown here since you need to be able to do simple sentences as well (all the types that you can already do).

Remember to do Regression Testing before, after and while you are expanding your grammar! Run the testsuite to make sure that you can still parse everything you want to parse in the right way.

S --> NP VP.

VP --> V { (NP) VPinf | CP}.

VPinf --> PARTinf VP.

CP --> C S. 

Hint: below is the tree commonly assumed for control constructions.

              S 
	    /   \
          /       \
        NP           VP 
        |          / \  \ 
      John       V    \   \
	    persuaded   NP  \
	    promised   / \    \
	              D   N    \
                     the cat  VPinf 
                              /  \
                         PARTinf  VP 
                           to    /  \
	                        V    NP
                               eat   |
                                    yoghurt

Note that the c-structure rules have not been annotated with any functional information as yet. You will need to do this. We went through how to implement these in class, so look back, think carefully about what you are doing and make sure you understand how the system is working.

You will also need to add control equations to the lexical entries for persuade, promise, want in the manner that is appropriate. Verbs selecting for a COMP don't contain a control equation (of course).

For example:

said   V * { (^ PRED) ='say<(^ SUBJ)(^ COMP)>'
	       |(^ PRED) = 'say<(^ SUBJ)(^ OBJ)>'}

convince  V * (^ PRED) = 'convince<(^ SUBJ)(^ OBJ)(^ XCOMP)>'
	      (^ OBJ) = (^ XCOMP SUBJ)

try 	  V * (^ PRED) ='try<(^ SUBJ)(^ XCOMP)>'
	      (^ SUBJ) = (^ XCOMP SUBJ)

Recursive Embedding

Make sure that your grammar allows for recursive embedding (it should already). The following sentences should work:

1. John persuaded Mary to want to eat beans.
2. John wanted Mary to think that Bill persuaded Kim to eat beans.
3. John thought that Mary wanted Bill to think that Kim wants to eat beans.

Control vs. Raising

Traditionally, a distinction is made between raising and control predicates. The intuition is that there is no thematic argument in so-called raising verbs. I.e., in examples like It seems to be raining., there is no actual "it" that is doing the raining. LFG encodes non-thematic arguments by placing them outside of the angle brackets, as shown in the sample lexical entry for seem. The control equations work exactly the same way as the control verbs we have already seen, such as convince, or try.

seem V * (^ PRED) = 'seem<(^XCOMP)>(^SUBJ)'
         (^ XCOMP SUBJ) = (^ SUBJ)

Modfiy your grammar so that the following sentences can be parsed.

1. It seems to be raining.
2. Mary seems to be eating a banana.

Relevant Reading Material

Dalrymple (2001), Chapter 12, pp. 313-330.

Cookbook, Sections 2.2, 2.3, 3.3-3.5