[lkb] Spanning only rules in the LKB

[Francis Bond]

G'day,

We have been adding more fragment rules to JACY.   It would be nice if
we could restrict some or all of them to be spanning only rules, as
one can in pet:

spanning-only-rules := $np-frag $pp-frag $int-adv-frag $pp-np-frag
                      $runon_s.

This has two advantages:

(1) it is more efficient:

Making the rules spanning only for pet reduces the number of tasks by
7.2%, and speeds things up by 5.1%.  And we have only 5 fragment rules
at the moment, compared to the ERG's almost 20.

(2) it is cleaner:

The fragment rules appear all over the place in the chart (although
not in the final parse), this makes it harder to debug using the chart view.

--
Francis Bond  <www.kecl.ntt.co.jp/icl/mtg/members/bond/>
NTT Communication Science Laboratories | Machine Translation Research Group