[developers] enhanced SEM-I support in the forthcoming 1214 release of the ERG

Ann Copestake aac10 at cl.cam.ac.uk
Fri Apr 29 17:21:33 CEST 2016

Great to have this!

Is there a specification of the semantics of the hierarchy anywhere?  I 
see there is multiple inheritance, but is it intended to be treated as 
the type hierarchy is, with glb types?  This was one of the unresolved 
issues that got in the way of implementation some years ago, as I 
remember it.  That is, glb types are not assumed in most KR formalisms 
but if we don't require them, then we end up with no deterministic 
single symbol corresponding to the combination of predicates.  If we are 
creating glb types automatically, this is in contrast to the behaviour 
assumed for the SEM-I in the past, which was that automatically created 
glb types are invalid in the output of a grammar.  If we're assuming 
that the developers always create them specifically, then that may be 
the best option, but obviously that needs to be explicit.

Incidentally, as I've mentioned to Dan (in the context of the tutorial), 
we've already started documentation of  ERS abstract predicates in 
Cambridge, but taking the opposite approach from the ongoing ERG 
Semantics pages, in that we feel the need to have at least very basic 
information about all the abstract predicates now.  We will release that 
very shortly, I hope.

All best,


On 29/04/2016 14:21, Stephan Oepen wrote:
> dear colleagues,
> woodley and i are currently working to implement a decade-old vision
> in ACE and the LKB, respectively: MRS manipulation in terms of the
> explicit SEM-I specification (rather than against the grammar-internal
> hierarchy).  we have had the SEM-I declare the inventory of most of
> the predicates and their synopses (sets of applicable argument labels
> and associated value constraints, if any) since around 2005.  but what
> has so far been missing was a specified inventory of available
> predicate abstractions and the hierarchical relations holding among
> them.  also, it turns out, there were missing some missing predicates
> that originate from specialization obtained during unification, e.g.
> the directional vs. stative vs. temporal sub-division of prepositional
> relations.
> in the forthcoming 1214 release of the ERG, the SEM-I has been
> extended with more thorough declarations of
> (0) the range of variable types, e.g. ‘i’ (for individuals), ‘e’ (for
> eventualities) and ‘x’ (for instances);
> (1) the inventory of variable properties and associated values, e.g.
> ‘PERS’(on) and ‘1’, ‘2’, and ‘3’;
> (2) a partial hierarchy of predicates and complete lists of legitimate
> surface and abstract predicates.
> i am writing to alert you to these changes and to maybe evoke some
> last-minute feedback on the imminent 1214 release.  you can inspect
> the new SEM-I files in the ‘etc/’ directory of the 1214 ERG (which is
> mapped to the ‘lingo/erg/’ directory of the LOGON tree) or straight
> from SVN:
>    http://svn.delph-in.net/erg/tags/1214/etc
> as before, ‘erg.smi’ is the top-level entry point containing (0) and
> (1) from the above list.  a small (manually maintained) part of the
> predicate hierarchy is in that file too, but the bulk of (2) above is
> distributed over ‘hierarchy.smi’, ‘abstract.smi’, and ‘surface.smi’.
> the current SEM-I exposes 121 abstract predicates, which dan, emily,
> and i hope to document (to at least some degree) as part of our
> ongoing ‘ErgSemantics’ efforts (see the corresponding wiki pages).
> this is in contrast to some 500 abstract, non-glb types in the
> grammar-internal predicate hierarchy, i.e. the SEM-I is masking a
> large number of distinctions that the ERG makes internally.
> so, in case you have used ERG predicate abstractions in the past (e.g.
> in MT work) that you feel are motivated and should be preserved for
> future generations, we would be grateful if you could try to identify
> any such predicates and look for them in the draft SEM-I for the 1214
> release.  with a much more tighter SEM-I now, i think it will be
> tempting to turn on pre-generation testing for SEM-I compliance at
> some point soon.  but we do expect that there will have to be more
> fine-tuning of SEM-I contents over time.
> to give you a better feel of what SEM-I abstractions can do for you,
> we have collected a handful of test cases in a new ‘mrs/’
> sub-directory of the ERG sources (in its forthcoming 1214 version),
> together with corresponding generator outputs from the LKB (woodley
> and i hope to compare between ACE and the LKB in the next few days):
> 0 oe at mv (~/src/logon/lingo/erg) 156 $ ls -l mrs/
> total 36
> -rw-r--r--. 1 oe oe    0 Apr 28 23:54 can_able.lkb
> -rw-r--r--. 1 oe oe  722 Apr 28 23:43 can_able.mrs
> -rw-r--r--. 1 oe oe   61 Apr 28 23:54 _in_p.lkb
> -rw-r--r--. 1 oe oe  898 Apr 28 23:35 _in_p.mrs
> -rw-r--r--. 1 oe oe 4028 Apr 28 23:54 nn.lkb
> -rw-r--r--. 1 oe oe  917 Apr 28 23:31 nn.mrs
> -rw-r--r--. 1 oe oe  130 Apr 28 23:54 temp_loc_sp.lkb
> -rw-r--r--. 1 oe oe  904 Apr 28 23:34 temp_loc_sp.mrs
> -rw-r--r--. 1 oe oe  136 Apr 28 23:54 universal_q.lkb
> -rw-r--r--. 1 oe oe  495 Apr 28 23:36 universal_q.mrs
> note that we take advantage of this new separation of church and state
> (i.e. the SEM-I vs. grammar-internal hierarchy, or maybe the other way
> around) to not only (a) hide many of the grammar-internal predicate
> distinctions, but also to (b) introduce additional abstractions not
> present in the grammar, and to (c) add some parent–child links between
> predicates that are ‘missing’ in the grammar.  an example of (b) is
> the sub-division of quantifiers into broad classes of existentials vs.
> universals and the (playful) addition of an abstraction over different
> ways of realizing an underspecified relation between two nominals,
> e.g. (from ‘nn.mrs’):
>    A jungle lion arrived.
>    A jungle's lion arrived.
>    A lion of a jungle arrived.
> an example of (c), finally, is making the temporal senses of
> prepositions like ‘at’, ‘in’, and ‘on’ specializations of the
> ‘general’ predicates associated with these prepositions, e.g.
>    _in_p_temp < temp_loc_sp & _in_p.
> —as regards software support, the following operations on MRSs can now
> optionally be keyed off the SEM-I rather than off the grammar-internal
> hierarchies:
> + initialization of the generator chart;
> + MRS comparison, including post-generation;
> + matching transfer rules to MRS fragments.
> in the LKB, there is a new global parameter *normalize-predicates-p*
> to enable SEM-I support for the above operations.  for the time being
> this mode is off by default (in the LKB) but will be enabled by
> default in the 1214 release of the ERG.  as of today, the
> *normalize-predicates-p* switch is only available for ongoing testing
> in the LOGON copy of the LKB, but i plan on pushing these changes
> upstream soon.  as a side-effect of MRS manipulation against the
> SEM-I, some of the corner cases we have discussed previously
> disappear: predicates are case-insensitive, the ‘_rel’ suffix is
> always stripped off, and there is no distinction made between (quoted)
> ‘strings’ and (unquoted) ‘types’.
> best wishes, oe

More information about the developers mailing list