Hmm it's curious you found determinization to be so costly since the Levenshtein automata are already determinized.
But, yeah, converting THAT to an FST is tricky... Mike McCandless http://blog.mikemccandless.com On Wed, May 25, 2016 at 2:46 PM, Luke Nezda <lne...@gmail.com> wrote: > Oof, sounds too tricky for me to justify pursuing right now. While > union'ing 10k Levenshtein automata was tractable, seems determinizing the > result is not (NP-hard - oops :)), let alone working out a suitably useful > conversion to an FST. > > Thank you very much for input! > > Kind regards, > - Luke > > On Tue, May 24, 2016 at 6:19 PM, Michael McCandless < > luc...@mikemccandless.com> wrote: > > > In theory if you could construct an FST from your union'd Levenshtein > > automata in the right format for SynonymFilter then you could run it > using > > that FST, and it would give you the start/end tokens for each match, and > > you'd have the output for each match be the original (unedited) terms. > > > > But I think information was already lost when you did the initial union, > > i.e. which original term to output, on which arc (s) in the automaton. > > > > Also you'd have to at least determinize (and maybe you want to minimize) > > the union'd automata since FST cannot represent non-deterministic > machines. > > > > Possibly you could determinize, reconstruct the lost information, by > > walking the automaton for each original word, intersecting the > Levenshtein > > automaton for that word, and recording the first arcs you hit that has > one > > unique original word as its output, and placing outputs on those arcs, > and > > then doing a "rote" conversion to the syn filter's FST format. This part > > sounds tricky :) > > > > Mike McCandless > > > > http://blog.mikemccandless.com > > > > On Tue, May 24, 2016 at 9:07 AM, Luke Nezda <lne...@gmail.com> wrote: > > > > > On Tuesday, May 24, 2016, Michael McCandless < > luc...@mikemccandless.com > > > <javascript:_e(%7B%7D,'cvml','luc...@mikemccandless.com');>> wrote: > > > > > > > This sounds ambitious ;) > > > > > > > > > That's why I was hoping for some advice from y'all :) > > > > > > > > > > > Note that Lucene has Levenshtein automata (not FSTs). > > > > > > > > > Right, but I thought it might not be too big a leap. > > > > > > > > > > > Can't you just run an AutomatonQuery on your index once you have > > unioned > > > > all Levenshtein automata into a single one? > > > > > > > > Or is the reason that you want to convert to an FST so you can > > associate > > > > which unedited form(s) a given document matched? > > > > > > > > > Correct, I want the unedited form(s) as well as the match character > > offsets > > > of each match in each document. > > > > > > > > > > > Mike McCandless > > > > > > > > http://blog.mikemccandless.com > > > > > > > > On Mon, May 23, 2016 at 8:59 PM, Luke Nezda <lne...@gmail.com> > wrote: > > > > > > > > > Hello, all - > > > > > > > > > > I'd like to use Lucene's automaton/FST code to achieve fast fuzzy > > (OSA > > > > edit > > > > > distance up to 2) search for many (10k+) strings (knowledge base: > kb) > > > in > > > > > many large strings (docs). > > > > > > > > > > Approach I was thinking of: create Levenshtein FST with all paths > > > > > associated with unedited form for each kb key, union all into > single > > > fst, > > > > > search docs for matches in fst in style of SynonymFilter. > > > > > > > > > > * I created 10k Levenshtein automata from kb keys and unioned > them, > > so > > > > > that seems tractable (took 1 minute, ~250MB ram) > > > > > * SynonymFilter code worked fine to associate output and record > match > > > > token > > > > > length. > > > > > * Saw how FuzzySuggester created Levenshtein automata from > > query/lookup > > > > key > > > > > and intersected that with kb-like fst. > > > > > > > > > > I don't see how to create Levenshtein FSTs (vs automatons) > > associating > > > > > outputs with unedited form, and union'ing them together. > > > > > > > > > > Is this a bad idea? Maybe better idea? > > > > > > > > > > Thanks in advance, > > > > > - Luke > > > > > > > > > > > > > > >
