Difference between revisions of "Talk:Automatically trimming a monodix"
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== HFST: possible to overcome compound overgeneration? == |
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==Alternate implementation methods== |
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Trimming while reading the XML file might have lower memory usage (who knows, untested), but seems like more work, since pardefs are read and turned into FST's before we get to an "initial" state and then attached at the end of regular entries. |
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Assuming we ''don't use flags'', we can compile an HFST transducer through [[ATT]] format to a working lttoolbox transducer. |
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[[Image:Product-automaton-intersection.png|thumb|400px|right|product automaton for intersection]] |
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The '''product automaton''' for intersection, marks as final only state-pairs where both parts of the state-pair are final in the original automata. Minimisation removes unreachable state-pairs. However, this quickly blows up in memory usage since it creates ''all'' possible state pairs first (cartesian product), not just the useful ones. |
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Now the issue is that compounds are plain transitions back into some lexicon, without the compound-only-L/compound-R tags, so even though lt-trim should trim the compounds correctly (by treating them like <j/> transitions), the resulting analyser will over-generate: |
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https://github.com/unhammer/lttoolbox/branches has some experiments, see e.g. branches product-intersection and df-intersection (the latter is the currently used implementation) |
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<pre>jīvitarēkha/jīvitarēkha<n><sg><nom>/jīvitaṁ<n><cmp>+rēkha<n><sg><nom></pre> |
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<br clear="all" /> |
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Ie. we will get non-lexicalised compound analyses along with the lexicalised ones. |
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== Compounds vs trimming in HFST == |
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One way to overcome this is to first compile the analyser from the ATT, then: |
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The sme.lexc can't be trimmed using the simple HFST trick, due to compounds. |
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* go through it building a new version, but on seeing a +, we: |
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** replace the transition with a single compound-only-L tag transitioning into final state |
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** let partial=copy_until_final(the_plus_transition) and make a transition from start into partial, and we connect the final state of partial with a single tag compound-R into the final state of our new FST |
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If the function copy_until_final sees a +, that transition is discarded, but a compound-only-L tag is added. |
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Say you have '''cake n sg''', '''cake n pl''', '''beer n pl''' and '''beer n sg''' in monodix, while bidix has '''beer n''' and '''wine n'''. The HFST method without compounding is to intersect '''(cake|beer) n (sg|pl)''' with '''(beer|wine) n .*''' to get '''beer n (sg|pl)'''. |
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But HFST represents compounding as a transition from the end of the singular noun to the beginning of the (noun) transducer, so a compounding HFST actually looks like |
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: '''((cake|beer) n sg)*(cake|beer) n (sg|pl)''' |
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The intersection of this with |
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: '''(beer|wine) n .*''' |
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is |
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: '''(beer n sg)*(cake|beer) n (sg|pl) | beer n pl''' |
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when it should have been |
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: '''(beer n sg)*(beer n (sg|pl)''' |
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Note: this compounding method won't let you do stuff like "only allow adj adj or noun noun compounds" like you can in HFST. |
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::You can do that in the morphotactics though (e.g. adjective paradigms only redirect to the adjectivestem lexicon.) - [[User:Francis Tyers|Francis Tyers]] ([[User talk:Francis Tyers|talk]]) 13:33, 22 May 2014 (CEST) |
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Lttoolbox doesn't represent compounding by extra circular transitions, but instead by a special restart symbol interpreted while analysing. |
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lt-trim is able to understand compounds by simply skipping the compund tags |
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: Uh, what happens if you simply specify compound-R and compound-only-L tags in the lexc? |
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::This is also an option, while we were at it I'd choose a prettier couple of symbols though ;) - [[User:Francis Tyers|Francis Tyers]] ([[User talk:Francis Tyers|talk]]) 13:33, 22 May 2014 (CEST) |
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Say we have the FST "bidix", can we create "<code>bidix [^+]* (+ bidix [^+]*)*</code>" (where + is just the literal join symbol) and trim with that? |
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: seems to work! |
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Latest revision as of 14:47, 20 June 2014
HFST: possible to overcome compound overgeneration?[edit]
Assuming we don't use flags, we can compile an HFST transducer through ATT format to a working lttoolbox transducer.
Now the issue is that compounds are plain transitions back into some lexicon, without the compound-only-L/compound-R tags, so even though lt-trim should trim the compounds correctly (by treating them like <j/> transitions), the resulting analyser will over-generate:
jīvitarēkha/jīvitarēkha<n><sg><nom>/jīvitaṁ<n><cmp>+rēkha<n><sg><nom>
Ie. we will get non-lexicalised compound analyses along with the lexicalised ones.
One way to overcome this is to first compile the analyser from the ATT, then:
- go through it building a new version, but on seeing a +, we:
- replace the transition with a single compound-only-L tag transitioning into final state
- let partial=copy_until_final(the_plus_transition) and make a transition from start into partial, and we connect the final state of partial with a single tag compound-R into the final state of our new FST
If the function copy_until_final sees a +, that transition is discarded, but a compound-only-L tag is added.
Note: this compounding method won't let you do stuff like "only allow adj adj or noun noun compounds" like you can in HFST.
- You can do that in the morphotactics though (e.g. adjective paradigms only redirect to the adjectivestem lexicon.) - Francis Tyers (talk) 13:33, 22 May 2014 (CEST)
- Uh, what happens if you simply specify compound-R and compound-only-L tags in the lexc?
- This is also an option, while we were at it I'd choose a prettier couple of symbols though ;) - Francis Tyers (talk) 13:33, 22 May 2014 (CEST)
Say we have the FST "bidix", can we create "bidix [^+]* (+ bidix [^+]*)*" (where + is just the literal join symbol) and trim with that?
- seems to work!
