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Hi Emily,<br>
<br>
Also quick replies ....<br>
<br>
<div class="moz-cite-prefix">On 29/06/2015 17:46, Emily M. Bender
wrote:<br>
</div>
<blockquote
cite="mid:CAMype6e=AsKbwUZKbv4mkH0KBs7usqEhxtPQJpGDni9jeCe=XQ@mail.gmail.com"
type="cite">
<div dir="ltr">Dear Ann,
<div><br>
</div>
<div>Thanks for the quick answers! Some further
comments/questions below:</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Fri, Jun 26, 2015 at 4:09 PM, Ann
Copestake <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:aac10@cl.cam.ac.uk" target="_blank">aac10@cl.cam.ac.uk</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">here's
some quick answers (on the basis I may never get round to
replying if I try and reply more carefully)<span><br>
<br>
On 26/06/2015 22:13, Emily M. Bender wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
Dear all,<br>
<br>
The UW group has been reading and discussing Copestake
et al 2001<br>
and Copestake 2007, trying to get a better
understanding of the MRS<br>
algebra. We have a few questions---I think some of
these issues have been<br>
proposed for the Summit, but I'm impatient, so I
thought I'd try to get<br>
a discussion going over email. UW folks: Please feel
free to chime in<br>
with other questions I haven't remembered just now.<br>
<br>
The two big ones are:<br>
<br>
(1) Copestake et al 2001 don't explicitly state what
the purpose of the<br>
algebra is. My understanding is that it provides a
guarantee that the MRSs<br>
produced by a grammar are well-formed, so long as the
grammar is<br>
algebra-compliant. Well-formed MRS (in this sense)
would necessarily<br>
have an interpretation because the algebra shows how
to compose the<br>
interpretation for each sement. Is this on track?
Are there other reasons<br>
to want an algebra?<br>
</blockquote>
<br>
</span>
We have never managed to prove that MRSs constructed
according to the algebra will be scopable, but I think
that is the case. But more generally, the algebra gives
some more constraints to the idea of compositionality
which isn't the case if you simply use feature
structures. It excludes some possible ways of doing
semantic composition and therefore constitutes a testable
hypothesis about the nature of the syntax-semantics
interface. It also allows one to do the same semantic
composition with grammars in formalisms other than typed
feature structures.<span><br>
<br>
</span></blockquote>
<div><br>
</div>
<div>I'm still trying to understand why it's important (or
maybe interesting is</div>
<div>the goal, rather than important?) to exclude some
possible ways of doing</div>
<div>semantic composition. Are there ways that are
problematic for some reason?</div>
<div>Is it a question of constraining the space of possible
grammars (e.g. for</div>
<div>learnability concerns)? Related to issues of
incremental processing?</div>
</div>
</div>
</div>
</blockquote>
<br>
The following may sound snarky but I really don't mean it this way -
would you have the same type of questions about syntactic
formalism? Because I can answer in two ways - one is about why I
think it's important to build testable formal models for language
(models which aren't equivalent to general programming languages, so
more constrained thn typed feature structures) and the other is
about what the particular issues are for compositional semantics. I
don't want to reach the conclusion that semantic composition
requires arbitrary programs without looking at more constrained
alternatives. So yes: learnability, processing efficiency (human
and computational), incrementality and so on, but one can't really
look at these in detail without first having an idea of plausible
models.<br>
<br>
<blockquote
cite="mid:CAMype6e=AsKbwUZKbv4mkH0KBs7usqEhxtPQJpGDni9jeCe=XQ@mail.gmail.com"
type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex"><span>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
Subquestions:<br>
<br>
(1a) I was a bit surprised to see the positing of
labels in the model. What<br>
would a label correspond to in the world? Is this
akin to reification of propositions?<br>
Are we really talking about all the labels here, or
just those that survive once<br>
an MRS is fully scoped?<br>
</blockquote>
<br>
</span>
the model here is not a model of the world - it's a model
of semantic structures (fully scoped MRSs).<span><br>
<br>
</span></blockquote>
<div><br>
</div>
<div>Oh, I missed that in the paper. So are we then talking
about "interpretation"</div>
<div>because the fully scoped MRSs are assumed to have
interpretations via </div>
<div>a second layer of modeling?</div>
</div>
</div>
</div>
</blockquote>
<br>
yes<br>
<br>
<blockquote
cite="mid:CAMype6e=AsKbwUZKbv4mkH0KBs7usqEhxtPQJpGDni9jeCe=XQ@mail.gmail.com"
type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex"><span>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
(1b) How does this discussion relate to what Ann was
talking about at IWCS<br>
regarding the logical fragment of the ERG and the rest
of the ERG? That is,<br>
if all of the ERG were algebra-compliant, does that
mean that all of the ERSs<br>
it can produce are compositional in their
interpretation? Or does that require<br>
a model that can "keep up"?<br>
</blockquote>
<br>
</span>
it's really orthogonal - what I was talking about at IWCS
was about the complete MRSs.<span><br>
<br>
</span></blockquote>
<div><br>
</div>
<div>Got it.</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex"><span>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
(2) Copestake et al state: "Since the constraints [=
constraints on grammar rules<br>
that make them algebra-compliant] need not be checked
at runtime, it seems<br>
better to regard them as metalevel conditions on the
description of the grammar,<br>
which can anyway easily be checked by code which
converts the TFS into the<br>
algebraic representation." What is the current
thinking on this? Is it in fact<br>
possible convert TFS (here I assume that means lexical
entries & rules?) to<br>
algebraic representation? Has this been done?<br>
<br>
</blockquote>
<br>
</span>
`easily' might be an exaggeration, but the code is in the
LKB, though it has to be parameterised for the grammar and
may not work with the current ERG. You can access it via
the menu on the trees, if I remember correctly. The small
mrscomp grammar is algebra compliant, the ERG wasn't
entirely when I tested it.<span><br>
<br>
</span></blockquote>
<div><br>
</div>
<div>In the spirit of keeping the discussion going without
delays, I haven't actually</div>
<div>played with this yet. But: accessible from the trees
seems to suggest that the</div>
<div>testing takes place over particular analyses of
particular inputs, and not directly</div>
<div>on the grammar as static code analysis. Is that right?</div>
<div><br>
</div>
</div>
</div>
</div>
</blockquote>
<br>
I think one could use static analysis based on that code on a
grammar which was very careful about not having pointers into the
semantics other than those licensed by the algebra. Either no such
pointers at all, or ones in which there was a clear locality, so it
was never possible for information to sneak back into the semantics
bypassing the official composition. Proving that can't happen with
a grammar like the ERG is difficult.<br>
<br>
<blockquote
cite="mid:CAMype6e=AsKbwUZKbv4mkH0KBs7usqEhxtPQJpGDni9jeCe=XQ@mail.gmail.com"
type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<div>Thanks again,</div>
<div>Emily</div>
<div><br>
</div>
</div>
</div>
</div>
</blockquote>
<br>
you're welcome! <br>
<br>
All best,<br>
<br>
Ann<br>
<br>
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