Thursday, May 28, 2015

Natural languages are SPARSE?

Here's a question for the community.  I was recently told by a referee, very succinctly, that "natural languages are sparse."  I believe he/she must have meant that natural languages are each members of the SPARSE complexity class of languages, defined here:
http://en.wikipedia.org/wiki/Sparse_language

While this seems reasonable at a glance, I have been at a loss to find any publication that proves, states, or otherwise mentions this putative fact.  Does anybody know how to establish whether natural languages are really sparse?

Friday, February 27, 2015

Mathematics of Language -- Call for Papers

Probably repetitive by now, but here is a repost of the official call.  I might even be in attendance.

14th Meeting on Mathematics of Language (MoL 2015)

July 25-26, 2015
University of Chicago, USA

http://www.molweb.org/mol2015/


# Third and Final Call for Papers

The Association for Mathematics of Language invites submissions to its
biennial conference, MoL, which will be held July 25-26, 2015, at the
University of Chicago.  The meeting takes place on the last weekend of
the Linguistic Summer Institute of the Linguistic Society of America.

## Description

MoL is devoted to the study of mathematical structures and methods
that are of importance to the description of language.  Contributions
to all areas of this field are welcome.  Specific topics within the
scope of the conference include, but are not limited to the following:

* formal and computational analysis of linguistic theories and frameworks
* learnability of formal grammars
* proof-theoretic, model-theoretic and type-theoretic methods in linguistics
* mathematical foundations of statistical approaches to language analysis
* formal models of language use and language change

## Invited Speakers

MoL will feature invited talks by the following distinguished
researchers:

* David McAllester (Toyota Technological Institute at Chicago, USA)
* Ryo Yoshinaka (Kyoto University, Japan)

## Submissions

MoL invites the submission of papers on original, substantial,
completed, and unpublished research.  Each submission will be reviewed
by at least three members of the program committee.  Papers presented
at the conference will be included in the conference proceedings,
which will be published in the ACL Anthology
(http://aclweb.org/anthology/).

All submissions must follow the style set out in the conference style
files, which are available at the conference website.  They must not
exceed twelve (12) pages of technical content, but may have an
unlimited number of extra pages for references.

Simultaneous submission to other conferences is allowed, provided that
the authors indicate which other conferences the paper is submitted
to.  A paper is accepted on the condition that it will not be
presented at any other venue.

MoL uses the EasyChair conference management system for submission,
reviewing and preparation of proceedings:

https://easychair.org/conferences/?conf=mol2015

Submissions must be uploaded to this system electronically in PDF
format no later than (end of day, Anywhere on Earth)

Friday, March 13, 2015

## Important Dates

* Paper submission deadline: March 13, 2015
* Notification of acceptance: April 24, 2015
* Camera-ready copy deadline: May 8, 2015
* Conference: July 25-26, 2015

## Program Committee

Marco Kuhlmann, Program Chair (Linköping University, Sweden)
Makoto Kanazawa, Program Co-Chair (National Institute of Informatics, Japan)
Greg Kobele, Local Chair (University of Chicago, USA)

Henrik Björklund (Umeå University, Sweden)
David Chiang (University of Notre Dame, USA)
Alexander Clark (King's College London, UK)
Shay Cohen (University of Edinburgh, UK)
Carlos Gómez-Rodríguez (University of A Coruña, Spain)
Jeffrey Heinz (University of Delaware, USA)
Gerhard Jäger (University of Tübingen, Germany)
Aravind Joshi (University of Pennsylvania, USA)
András Kornai (Hungarian Academy of Sciences, Hungary)
Giorgio Magri (CNRS, France)
Andreas Maletti (University of Stuttgart, Germany)
Jens Michaelis (Bielefeld University, Germany)
Gerald Penn (University of Toronto, Canada)
Carl Pollard (The Ohio State University, USA)
Jim Rogers (Earlham College, USA)
Mehrnoosh Sadrzadeh (Queen Mary University of London, UK)
Sylvain Salvati (INRIA, France)
Ed Stabler (University of California, Los Angeles, USA)
Mark Steedman (Edinburgh University, UK)
Anssi Yli-Jyrä (University of Helsinki, Finland)

## Contact

For inquiries about the scientific program of the conference, please
email mol2015@easychair.org.

For inquiries about the local organization and all practical aspects
of the conference, please email mol2015.chicago@gmail.com.

Modeling the changes of natural vowel systems

Back in 2013, I posted about my plans to write a computer simulation that could model the way vowel systems are learned, transmitted, and changed.  I am happy to report that the first phase of this project was completed, and we presented a poster at the AAAS meeting this month.  I was able to find an excellent student of computer science, Hannah Scott, who is now my coauthor on the project.  She programmed the entire simulation in Python, leveraging methods from the "imitation game" described by Luc Steels.

In our simulation, we begin with a vowel system, which is just a set of F1 and F2 values on a vowel chart. Then some number of agents we call "parents" says the vowels a number of times to each of the "children."  The children then try to repeat the vowels, and we provide feedback based on how accurate the repetition is.  All of this has random noise introduced, of course, and the main parameters are the children's precision and the tolerance of the feedback system.

We had originally conceived of the feedback as coming from the parents, but then colleagues pointed out that in reality, parents' feedback is not used by children learning the sounds of language.  The real feedback comes from the child's own brain, which has already learned and stored an excellent perceptual model of the correct vowels.  The child is perfectly capable of monitoring and critiquing his/her own production efforts.

The simulation is, as might be expected, very sensitive to the values of the precision and tolerance parameters.  When either of these is too large or too small, the vowel system goes haywire or is completely extinct in one or two generations.  The sweet spot for these parameters, so far, is around 1 Equivalent Rectangular Bandwidth (an auditory unit of frequency).

We obtained some interesting little results so far.  E.g. the simulation preserves the Spanish 5-vowel system perfectly for eternity, but with the same parameters applied to the English vowels there are changes, with vowels merging etc.  These changes are then mitigated by introducing vowel duration as an additional attribute.  In my opinion this behavior of the simulation is incredibly realistic for a first try.

And this indeed seems to be *the first* attempt to do this.  I could find nothing in literature that presented a simulation of sound change, whether for vowels or anything at all. There is, of course, the literature by Steels and Bart de Boer which models how vowel systems could have emerged in the first place, at the dawn of language, but that is really a different type of question.