Constituent Structure - Part 24 | 10 PRELIMINARIES Moving from left to right on the page we combine two elements creating a new object then we combine2 this new structure with the next word to the right and so on. 4 a Nemo ate b Nemo ate Dory s c Nemo ate Dory s seaweed d Nemo ate Dory s seaweed Let us call this the structured-concatenation hypothesis. This approach does not suffer from the problem of 2 in that any subpart of 4d is not identical to a subpart of any of the strings in 3 . For example the first concatenation in 4 is not identical to the first concatenation of 3b 5 Nemo ate Dory ate This is what we want since we do not want sentence 2 to mean the same thing as 3b . Nevertheless the structured concatenation hypothesis suffers in a different important way. If you look closely at the brackets in 4d you will note that Dory s is structurally closer to ate than it is to seaweed. We can capture this more precisely by counting the number of parentheses enclosing each item. If we were to number matching opening and closing parens we get the annotated structure in 6 6 1 2 3Nemo ate 3 Dory s 2 seaweed 1 You will note that all of Nemo ate Dory s are enclosed in the 2 2 parentheses. Seaweed is excluded from this set. In this set-theoretic sense then Dory s is closer to ate than it is to seaweed. However this flies in the face of native-English-speaker intuitions about what words go together with one another. On an intuitive level we know that Dory s has a closer semantic relationship to seaweed than it does to ate. You might think we could get around this problem by reversing the order of concatenation and starting at the right. Indeed for the example sentence 1 this gives us a structure corresponding to the intuition about the closeness of Dory and seaweed 2 I use the symbol ffi here roughly in the sense in which it is used in Head Driven Phrase Structure Grammar HPSG as a list-addition operator which is not commutative a ffi b b ffi a. Though technically speaking ffi operates over set-theoretic .
