Notes on computational linguistics.pdf - UCLA Department of ...

Stabler - Lx 185/209 2003
10.6.4 Coordination
Coordination structures are common across languages, and pose some interesting problems for our grammar.
Notice that we could parse:
Titus praise -s the coffee and pie
Titus laugh -s or Lavinia laugh -s
Titus be -s happy and proud
by adding lexical items like these to the grammar gh4.pl:
But this approach will not work for
and::=N =N N and::=C =C C and::=A =A A
or::=N =N N or::=C =C C or::=A =A A
Titus praise -s Lavinia and Tamara.
The reason is that each name needs to have its case checked, but in this sentence there are three names (Titus,
Lavinia, Tamara) and only two case checkers (-s, praise). We need a way to coordinate Lavinia and Tamara that
leaves us with just one case element to check. Similar problems face coordinate structures like
Titus and Lavinia will -s laugh
Titus praise -s and criticize -s Lavinia
Who -s Titus praise and criticize
Titus can and will -s laugh
Some and every king will -s laugh
For this and other reasons, it is commonly thought that coordination requires some kind of special mechanism
in the grammar, unlike anything we have introduced so far (Citko, 2001; Moltmann, 1992; Munn, 1992).
One simple idea is that the grammar includes a special mechanism that is analogous to the adjunction mechanism
above, which for any coordinator x :: coord and any phrases s · α and t · α, attaching the first argument
on the right as complement and later arguments as specifiers. More precisely, we use the following ternary
rule:
sh :: coord ts,th,tc · γ,α1,...,αk us,uh,uc · γ,α1,...,αk
coord1
tsthtc,sh,usuhuc : γ,α1,...,αk
Allowing γ to be any sequence of features (with the requirement that the coordinated items s and t have this
same sequence of features) will have the result that the two case requirements of the names in Lavinia and
Tamara will be combined into one. The requirement that the moving constituents α1,...αk match exactly will
give us a version of the “across-the-board” constraint on movements.
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