Andrei Popescu

I am a Senior Lecturer at the Middlesex University London, School of Science and Technology, in the Foundations of Computing and Applied Software Engineering research groups. Previously, I worked as a researcher at the Informatics Institute, Technical University Munich, at the Chair for Logic and Verification headed by Tobias Nipkow and patroned by goddess Isabelle. Further down in the past, I did my Ph.D. in computer science at the University of Illinois at Urbana-Champaign, advised by Elsa L. Gunter and Grigore Roșu. Even further back, when I was really really young, I did my Ph.D. in mathematics at the University of Bucharest, advised by George Georgescu.

Some resources for students

Dear students, please read this text (by Luca Aceto) if you are wondering what on earth does an academic do when they are not teaching.

News and events I am involved in

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Research

My research topics are proof assistants, inductive and coinductive datatypes, automated deduction, syntax with bindings and information flow security.

● In Munich, I was the initiator of a project aimed at designing and implementing a novel datatype specification mechanism for Isabelle/HOL, covering state-of-the-art mutual and nested inductive and coinductive datatypes based on insight from category theory. The project's success, measured in the large and growing number of happy users of the new (co)datatype package, is largely due to my brilliant collaborators, Jasmin Blanchette and Dmitriy Traytel, who contributed to the design and did most of the implementation. Our results, summarized (and some, anticipated) in my ESOP'15 slides, are reported in several papers: LICS'12, IJCAR'14, ITP'14, ESOP'15, ICFP'15, ESOP'17, LICS'17. Some of my related work includes non-free datatypes (CPP'13) and first- and higher- order abstract syntax (LICS'10, ICFP'11, TCS 2015), all materialized in Isabelle/HOL.

● I also work on the logical foundations of proof assistants based on higher-order logic. In particular, Isabelle/HOL extends the traditional version of HOL used in theorem proving (due to Mike Gordon) in a non-trivial way to accommodate ad hoc overloading. In turn, this enables Haskel-style type classes, leading to lighter developments. One could even argue that type classes are a key ingredient behind Isabelle/HOL's popularity. Together with Ondřej Kunčar, I have shown that Isabelle/HOL's logic is consistent, by two alternative proofs: one based on a non-standard semantics of HOL (ITP'15), and a proof-theoretic one (ESOP'17). Our most recent result (POPL'18) improves on these results by establishing the stronger properties of meta-safety and conservativity. We have also proposed (and proved consistent) an extension of Isabelle/HOL with local type definitions (ITP'16) improving on the traditional HOL typedef.

● Another line of research where I invest a lot of my enthusiasm is the mechanical verification of information-flow security; I believe we can have systems that are both verified and usable. In this area, the results I am most proud of are two entities, named CoCon and CoSMeDis. CoCon is a realistic conference management system verified for confidentiality (CAV'14). So far, it has been used for the Tableaux 2015 and ITP 2016 conferences. I am grateful to RS3 for supporting and encouraging this research as a reference scenario. CoSMeDis is a prototype distributed social media platform (ITP'16, Security and Privacy '17) developed jointly with an industrial partner, Global Notice Board. Both systems are built around kernels that are verified not to leak confidential information. In addition, CoSMeDis has been verified following a compositional methodology: Single-node guarantees are extended to the whole distributed network - more details here.

● Jasmin, myself and collaborators have been working at designing and formalizing sound, complete and efficient translations of Isabelle's higher order logic to the first order language spoken by (fully) automated theorem provers and SMT solvers, in order to boost Isabelle's automation (ITP'12, TACAS'13, FroCoS'13). These encodings are implemented in the Sledgehammer tool, which connects Isabelle with other mythological creatures such as E, SPASS, Vampire, CVC4 and Z3. My FroCoS slides give an overview.

● In the past, I worked on fuzzy logic and abstract model theory. My joint work with Daniel Găină on general formulations of the Robinson consistency and elementary chain theorems has been included in the standard reference book on institution-independent model theory.


Research supervision
Complete list of publications and drafts (many also on DBLP)

On formal methods

  1. Draft Jasmin Christian Blanchette, Lorenzo Gheri, Andrei Popescu, Dmitriy Traytel General Bindings as Functors Submitted

  2. Preprint Ondřej Kunčar, Andrei Popescu Safety and conservativity of definitions in HOL and Isabelle/HOL POPL 2018
    Article No. 24, 1-24, ACM

  3. Preprint Jasmin Christian Blanchette, Fabian Meier, Andrei Popescu, Dmitriy Traytel Foundational nonuniform (co)datatypes for higher-order logic LICS 2017
    1-12, ACM / IEEE

  4. Draft Thomas Bauereiß, Armando Pesenti Gritti, Andrei Popescu, Franco Raimondi CoSMeDis: A Distributed Social Media Platform with Formally Verified Confidentiality Guarantees Security and Privacy 2017
    729-748, IEEE

  5. Preprint Ondřej Kunčar, Andrei Popescu Comprehending Isabelle/HOL's consistency ESOP 2017
    LNCS 10201, 724-749, Springer

  6. Preprint Jasmin Christian Blanchette, Aymeric Bouzy, Andreas Lochbihler, Andrei Popescu, and Dmitriy Traytel Friends with benefits: Implementing corecursion in foundational proof assistants ESOP 2017
    LNCS 10201, 111-140, Springer

    Here are the slides for my two end-to-end ESOP 2017 talks.

  7. Draft Jasmin Christian Blanchette, Andrei Popescu, Dmitriy Traytel Soundness and completeness proofs by coinductive methods Journal of Automatic Reasoning 58(1): 149-179 (2017) (Special issue dedicated to IJCAR 2014)

  8. Preprint Lorenzo Gheri, Andrei Popescu A Formalized General Theory of Syntax With Bindings ITP 2017
    LNCS 10499, 241-261, Springer

  9. Draft Jasmin Christian Blanchette, Sascha Böhme, Andrei Popescu, Nicholas Smallbone Encoding monomorphic and polymorphic types Logical Methods in Computer Science 12(4), 2016 (Special issue dedicated to TACAS 2013)

  10. Preprint Thomas Bauereiß, Armando Pesenti Gritti, Andrei Popescu, Franco Raimondi CoSMed: A Confidentiality-Verified Social Media Platform ITP 2016
    LNCS 9807, 87-106, Springer

  11. Preprint Ondřej Kunčar, Andrei Popescu From Types to Sets by Local Type Definitions in Higher-Order Logic ITP 2016
    LNCS 9807, 200-218, Springer

  12. Preprint Jasmin Christian Blanchette, Andrei Popescu, Dmitriy Traytel Foundational Extensible Corecursion: A Proof Assistant Perspective ICFP 2015
    192-204, ACM

  13. Preprint Slides Jasmin Christian Blanchette, Andrei Popescu, Dmitriy Traytel Witnessing (Co)datatypes ESOP 2015
    LNCS 9032, 359-382, Springer

  14. Preprint Andrei Popescu, Grigore Roșu Term-Generic Logic Theoretical Computer Science 577: 1–24 (2015)

  15. Preprint Ondřej Kunčar, Andrei Popescu A Consistent Foundation for Isabelle/HOL ITP 2015
    LNCS 9236, 234-252, Springer

  16. Preprint Slides Sudeep Kanav, Peter Lammich, Andrei Popescu A Conference Management System with Verified Document Confidentiality CAV 2014
    LNCS 8559, 167-183, Springer

  17. Preprint Jasmin Christian Blanchette, Johannes Hölzl, Andreas Lochbihler, Lorenz Panny, Andrei Popescu, Dmitriy Traytel Truly Modular (Co)datatypes for Isabelle/HOL ITP 2014
    LNCS 8558, 93-110, Springer

  18. Preprint Slides Jasmin Christian Blanchette, Andrei Popescu, Dmitriy Traytel Cardinals in Isabelle/HOL ITP 2014
    LNCS 8558, 111-127, Springer

  19. Preprint Tobias Nipkow, Andrei Popescu Making Security Type Systems Less Ad Hoc it - Information Technology 56(6): 267-272 (2014)

  20. Preprint Jasmin Christian Blanchette, Andrei Popescu, Dmitriy Traytel Unified Classical Logic Completeness: A Coinductive Pearl IJCAR 2014
    LNCS 8562, 46-60, Springer

  21. Preprint Ondřej Kunčar, Andrei Popescu From Types to Sets in Isabelle/HOL Isabelle Workshop 2014

  22. Preprint Slides Andreas Schropp, Andrei Popescu Nonfree Datatypes in Isabelle/HOL: Animating a Many-Sorted Metatheory CPP 2013
    LNCS 8307, 114-130, Springer

  23. Preprint Slides Andrei Popescu, Johannes Hölzl, Tobias Nipkow Formalizing Probabilistic Noninterference CPP 2013
    LNCS 8307, 259-275, Springer

  24. Preprint Andrei Popescu, Johannes Hölzl, Tobias Nipkow Formal Verification of Language-Based Concurrent Noninterference Journal of Formalized Reasoning 6(1), 2013

  25. Preprint Slides Jasmin Christian Blanchette, Andrei Popescu Mechanizing the metatheory of Sledgehammer FroCoS 2013
    LNCS 8152, 245-260, Springer

  26. Preprint Slides Andrei Popescu, Johannes Hölzl, Tobias Nipkow Noninterfering Schedulers: When Possibilistic Noninterference Implies Probabilistic Noninterference CALCO 2013
    LNCS 8089, 236-252, Springer

  27. Preprint Jasmin Christian Blanchette, Sascha Böhme, Andrei Popescu, Nicholas Smallbone Encoding Monomorphic and Polymorphic Types TACAS 2013
    LNCS 7795, 493-507, Springer

  28. Preprint Andrei Popescu, Johannes Hölzl, Tobias Nipkow Proving Concurrent Noninterference CPP 2012
    LNCS 7795, 109-125, Springer
    Proud receiver of the RS3 best paper award for 2012-2013

  29. Preprint Jasmin Christian Blanchette, Andrei Popescu, Daniel Wand, Christoph Weidenbach More SPASS with Isabelle - Superposition with Hard Sorts and Configurable Simplification ITP 2012
    LNCS 7406, 345-360, Springer

  30. Preprint Slides Dmitriy Traytel, Andrei Popescu, Jasmin Christian Blanchette Foundational, Compositional (Co)datatypes for Higher-Order Logic: Category Theory Applied to Theorem Proving LICS 2012
    596-605, IEEE

  31. Preprint Andrei Popescu, Elsa L. Gunter Recursion principles for syntax with bindings and substitution ICFP 2011
    346-358, ACM

  32. Preprint Slides Slides Andrei Popescu, Elsa L. Gunter, Christopher J. Osborn Strong Normalization for System F by HOAS on Top of FOAS LICS 2010
    31-40, IEEE

  33. Preprint Slides Andrei Popescu, Elsa L. Gunter Incremental Pattern-Based Coinduction for Process Algebra and Its Isabelle Formalization FOSSACS 2010
    LNCS 6014, 109-127, Springer

  34. Preprint Andrei Popescu, Traian Florin Șerbănuță, Grigore Roșu A semantic approach to interpolation Theoretical Computer Science 410(12-13): 1109-1128 (2009)

  35. Preprint Slides Andrei Popescu Weak Bisimilarity Coalgebraically CALCO 2009
    LNCS 5728, 157-172, Springer

  36. Elsa L. Gunter, Christopher J. Osborn, Andrei Popescu Theory support for weak higher order abstract syntax in Isabelle/HOL LFMTP 2009
    12-20, ACM

  37. Preprint Andrei Popescu, Grigore Roșu Term-Generic Logic. WADT 2008
    LNCS 5486, 290-307, Springer

  38. Daniel Găină, Andrei Popescu An Institution-Independent Proof of the Robinson Consistency Theorem Studia Logica 85(1): 41-73 (2007)

  39. Daniel Găină, Andrei Popescu An Institution-independent Generalization of Tarski's Elementary Chain Theorem Journal of Logic and Computation 16(6): 713-735 (2006)

  40. Andrei Popescu, Traian Florin Șerbănuță, Grigore Roșu A Semantic Approach to Interpolation FOSSACS 2006
    LNCS 3921, 307-321, Springer

  41. Preprint Andrei Popescu, Grigore Roșu Behavioral Extensions of Institutions CALCO 2005
    LNCS 3629, 331-347, Springer

  42. Andrei Popescu Languages Generated Using an Abstract Catenation Grammars 7: 31-40 (2004)

Ph.D. thesis

  1. Preprint   Contributions to the Theory of Syntax with Bindings and to Process Algebra University of Illinois at Urbana-Champaign (2010)
    Advisor: Elsa Gunter

Isabelle Developments in The Archive of Formal Proofs

  1. Andrei Popescu, Peter Lammich Bounded-Deducibility Security Archive of Formal Proofs (2014)

  2. Markus N. Rabe, Peter Lammich, Andrei Popescu A shallow embedding of HyperCTL* Archive of Formal Proofs (2014)

  3. Andrei Popescu, Johannes Hölzl Probabilistic Noninterference Archive of Formal Proofs (2014)

  4. Jasmin Christian Blanchette, Andrei Popescu, Dmitriy Traytel Abstract Completeness Archive of Formal Proofs (2014)

  5. Jasmin Christian Blanchette, Andrei Popescu Sound and Complete Sort Encodings for First-Order Logic Archive of Formal Proofs (2013)

  6. Andrei Popescu, Johannes Hölzl Possibilistic Noninterference Archive of Formal Proofs (2012)

  7. Andrei Popescu Ordinals and Cardinals Archive of Formal Proofs (2009)

On fuzzy logic and algebra

  1. Andrei Popescu Some algebraic theory for many-valued relation algebras Algebra Universalis 56: 211-235 (2007)

  2. George Georgescu, Andrei Popescu A common generalization for MV-algebras and Lukasiewicz-Moisil algebras Archive for Mathematical Logic 45(8): 947-981 (2006)

  3. George Georgescu, Ioana Leustean, Andrei Popescu Order convergence and distance on Lukasiewicz-Moisil algebras Journal of Multiple-Valued Logic and Soft Computing 12(1-2): 33-69 (2006)

  4. George Georgescu, Andrei Popescu A new class of probabilities on Lukasiewicz-Moisil algebras Journal of Multiple-Valued Logic and Soft Computing 12(3-4): 337-354 (2006)

  5. George Georgescu, Andrei Popescu Similarity Convergence in Residuated Structures Logic Journal of the IGPL 13(4): 389-413 (2005)

  6. Andrei Popescu Lukasiewicz-Moisil Relation Algebras Studia Logica 81(2): 167-189 (2005)

  7. Andrei Popescu Many-Valued Relation Algebras Algebra Universalis 53: 73-108 (2005)

  8. George Georgescu, Andrei Popescu Non-dual fuzzy connections Archive for Mathematical Logic 43(8): 1009-1039 (2004)

  9. George Georgescu, Andrei Popescu Non-commutative fuzzy structures and pairs of weak negations Fuzzy Sets and Systems 143(1): 129-155 (2004)

  10. Andrei Popescu A general approach to fuzzy concepts Mathematical Logic Quarterly 50(3): 265-280 (2004)

  11. George Georgescu, Andrei Popescu Non-commutative fuzzy Galois connections Soft Computing 7(7): 458-467 (2003)

  12. George Georgescu, Andrei Popescu Concept lattices and similarity in non-commutative fuzzy logic Fundamenta Informaticae 53(1): 23-54 (2002)