This is an announcement for a postdoc position opening at Université ParisSud, working on the interplay between Data, Knowledge, and Software in Mathematics, and in particular the exploitation of mathematical knowledge for increased interoperability across computational mathematics software and mathematical databases.
Time line
Interviews in early december, for a recruitment from early 2018 to Fall 2019. Since we have a strong candidate for a half time position, we will also consider candidates interested in a halftime or shorter duration position.
Salary
For a fulltime month work and depending on the applicant’s past experience, between 2000€ and 3000€ of monthly “salaire net” (salary after nonwage abour cost but before income tax).
Equivalently, what this salary represents for is a “salaire brut” of up to 46200€ yearly (for a fulltime position).
Location
The postdoc will work at the Laboratoire de Recherche en Informatique of Université Paris Sud, in the OrsayBuresGifSaclay campus, 25 km SouthWest of Paris city centre.
Mission and activities
OpenDreamKit’s Work Package 6 explores the interplay between Data, Knowledge and Software in Mathematics. In particular, it aims at exploiting mathematical knowledge for increased interoperability across computational mathematics software and mathematical databases (known as the MathInTheMiddle approach). See e.g. the recent publications on that topic, and Section 3.1.6 ``Workpackage Description’’ of the OpenDreamKit Proposal.
A successful candidate will be expected to do significant progress, in close collaboration with the other OpenDreamKit participants and the community, on some of the tasks of this Work Package:

D6.8: Currated MathintheMiddle Ontology and Alignments for GAP / Sage / LMFDB

T6.5: Knowledgebased code infrastructure
Over the last decades, computational components, and in particular Axiom, MuPAD, \GAP, or \Sage, have embedded more and more mathematical knowledge directly inside the code, as a way to better structure it for expressiveness, flexibility, composability, documentation, and robustness. In this task we will review the various approaches taken in these software (e.g. categories and dynamic class hierarchies) and in proof assistants like Coq (e.g. static type systems), and compare their respective strength and weaknesses on concrete case studies. We will also explore whether paradigms offered by recent programming languages like Julia or Scala could enable a better implementation. Based on this we will suggest and experiment with design improvements, and explore challenges such as the compilation, verification, or interoperability of such code.
The candidate will be welcome to work on closely related though more technical tasks:

T4.5: Dynamic documentation and exploration system
Introspection has become a critical tool in interactive computation, allowing user to explore, on the fly, the properties and capabilities of the objects under manipulation. This challenge becomes particularly acute in systems like Sage where large parts of the class hierarchy is built dynamically, and static documentation builders like Sphinx cannot anymore render all the available information.
In this task, we will investigate how to further enhance the user experience. This will include:

On the fly generation of Javadoc style documentation, through introspection, allowing e.g. the exploration of the class hierarchy, available methods, etc.

Widgets based on the HTML5 and web component standards to display graphical views of the results of SPARQL queries, as well as populating data structures with the results of such queries,

D4.16: Exploratory support for semanticaware interactive widgets providing views on objects of the underlying computational or database components. Preliminary steps are demonstrated in the Larch Environment project (see demo videos) and sageexplorer. The ultimate aim would be to automatically generate LMFDBstyle interfaces.
Whenever possible, those features will be implemented generically for any computation kernel by extending the Jupyter protocol with introspection and documentation queries.


T6.9: Memoisation and production of new data
Many CAS users run large and intensive computations, for which they want to collect the results while simultaneously working on software improvements. GAP retains computed attribute values of objects within a session; Sage currently has a limited
cached_method
. Neither offers storage that is persistent across sessions or supports publication of the result or sharing within a collaboration. We will use, extend and contribute back to, an appropriate established persistent memoisation infrastructure, such aspythonjoblib
,redissimplecache
ordogpile.cache
, adding features needed for storage and use of results in mathematical research. We will design something that is simple to deploy and configure, and makes it easy to share results in a controlled manner, but provides enough assurance to enable the user to rely on the data, give proper credit to the original computation and rerun the computation if they want to.
Skills and background requirements

Strong experience in the design and practical implementation of mathematics software: computational mathematics software (e.g. SageMath), knowledge management systems, or proof systems;

PhD in mathematics or computer science;

Experience in opensource development (collaborative development tools, interaction with the community, …);

Fluency in programming languages such as Scala, Python, Julia, etc appreciated;

Strong communication skills;

Fluency in oral and written English; speaking French is not a prerequisite.
Context
The position will be funded by
OpenDreamKit, a Horizon 2020 European Research Infrastructure project that will run for four years, starting from September
 This project brings together the opensource computational mathematics ecosystem – and in particular LinBox, MPIR, SageMath, GAP, PARI/GP, LMFDB, Singular, MathHub, and the IPython/Jupyter interactive computing environment. – toward building a flexible toolkit for Virtual Research Environments for mathematics. Lead by Université ParisSud, this project involves about 50 people spread over 15 sites in Europe, with a total budget of about 7.6 million euros.
Within this ecosystem, the developer will work primarily on the free opensource mathematics software system Sagemath. Based on the Python language and many existing opensource math libraries, SageMath is developed since 10 years by a worldwide community of 300 researchers, teachers and engineers, and has reached 1.5M lines of code.
The developer will work within one of the largest teams of SageMath developers, composed essentially of researchers in mathematics and computer science, at the Laboratoire de Recherche en Informatique (LRI) and in nearby institutions. The LRI also hosts a strong team working on proof systems.
Applications
To apply for this position, please send an email to Nicolas.Thiery at upsud.fr before December 1st, with the following documents attached:

cover_letter.pdf: a cover letter, in English (why are you interested in this particular position);

CV.pdf: a CV, highlighting among other things your skills and background and your contributions to open source software;

phd_reports.pdf: PhD reports (when applicable);

reference letters (each named reference_letter_
.pdf), or alternatively reference contact information.
Applications sent after December 1st will be considered until the position is filled.