Assignment 3 grading and comments

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Problem 1

Grads 55, Undergrads 40, a - 10 marks per sentence, total 40, b(grads only) - 3 marks per item, total 15

A common problem for all trees was incorrectly specifying feature values. Note that PP does not have case, agreement or other features, except for pform and wh.

Another difficult question is recognizing PP's and adverbials. Phrases such as "where" can correspond to either PP's or true adverb phrases, such as "there". It it therefore possible to analyze them as PP's, though they are adverbials from the point of view of semantics, and phrases like "at home" can coordinate with adverbs like "there". Therefore it is better to analyze such PP's as adverbial modifiers, using the rule

  ADVL -> PP[pred]
  
I marked the cases when the PP analysis was adopted, but didn't take points off for that. The only truly incorrect analysis that someone adopted was
  PP -> ADVL
  

a

Almost everyone did the question correctly. Most common mistakes were incorrectly specifying feature values for nodes.

b

People did generally well on that, though not everyone identified "The key you mislaid" as the subject NP containing relative clause.

c

The most important part of the question was recognizing symmetry that exists in the sentence: both verbs take an adverbial (or PP if you wish) complement, so both should have the gap of the same type. Not everyone noticed that.

d

Most people were thoroughly confused by this sentence. Note that the rule for comparative structures states
  NP -> NP[+er] than XP[/NP]
  
where XP can be S, PP or other NP. So the phrase sentence should be analyzed as
  [S Phil bought [NP [NP more jewelry] than [S [S Fran wanted t] or [S he could afford t]]]] 
                 NP-> NP               than S/NP  
  

Problem 2

33 marks, 4 per sentence, 5 for conclusions

One important thing to note there is that what results you get for RA and MA is the matter of syntactic analysis you adopt. There is no exact answer, and different theories produce different results. There are competing analyses of the sentence depending on how seriously you take Xbar theory and which rules you adopt for prepositional phrase adjuncts (some theories allow them to modify the verb head, while others don't), and how do you define verb complements versus adjuncts, which is sometimes a difficult question. Therefore it is absolutely necessary to draw phrase structure trees in your arguments to show the exact structure of the sentence you're assuming. Some people got results opposite from mine because they had different trees. I accepted every analysis as long as it was plausible, but I took off points if I could not figure out what exact phrase structure you were assuming.

Problem 3

10 marks

Most people did very well of that. The most common problem was assuming that "born" was a base form of the verb. It is apparently not, but rather the past participle of "bear". The other difficult question is whether "In which town" is the adverbial modifier that modifies the whole VP (this was the analysis that I adopted) or it is subcategorized for by the verb. You can make arguments for both cases, so I considered either analysis correct.

Problem 4

Undergrads - 15, grads a-7, b-3, c-6, d-4, total 20

People generally did very well on that problem, too.

Problem 5

a - 6, b - 2 marks per item, total 12

Everyone did very well on that, except maybe for item 2 in b. Note that A and B being dependent(independent) does not mean that they will be dependent(independent) given C.

Consider the following situation: A and B are independent events that can cause C, for example, both spilled oil and soap on the bathroom floor can cause you to slip. But after you have already slipped, it is conceivable to that knowing that there was probably soap on the floor lowers the probability that oil was spilled, too, so P(A|B,C) <> P(A,C).

Similarly, A and B an be dependent if A causes C and C causes B, like when slipping can cause you fall down, and falling down can cause breaking a leg, so slipping and breaking the leg are not independent. However, if we already know that you fell down, it is possible to say that knowing that you slipped on the spilled oil rather than tripped over something does not influence the probability of your breaking the leg. Therefore A and B are conditionally independent given C.

If you're interested, I can give you a good explanatory article that deals with problems of events being conditionally independent within the Bayes net framework.

Statistics

Here are the scores so that you can compare your performance to others.

(grads max 130, undergrads max 110)

  51.50
  92.00
  97.00
  98.00
  122.00