Recent and upcoming talks by Frank Stephan

Frank Stephan: Finitely generated semiautomatic groups

Update on the Logic Seminar at the National University of Singapore (the originally announced speaker is ill and will speak on 12 April 2017) Date: Wednesday, 22 March 2016, 17:00 hrs Room: S17#04-05, Department of Mathematics, NUS Speaker: Frank Stephan Title: Finitely generated semiautomatic groups URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html The present work shows that Cayley automatic groups are semiautomatic and exhibits some further constructions of semiautomatic groups. continue reading…

Frank Stephan: On block pumpable languages

Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, Wednesday 10 Aug 2016, 17:00 hrs Room: S17#04-05, Department of Mathematics, NUS Speaker: Frank Stephan Title: On block pumpable languages URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html Abstract: Call a language L block pumpable iff there is a constant p>1 such that for every splitting of a word in the language L into p+1 blocks, one can find a subword consisting of an interval of the interior blocks such that each modified word obtained by repeating or omitting this subword is also in the language L. continue reading…

Frank Stephan: Learning automatatic families of languages

Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 9 March 2016, 17:00 hrs Room: S17#05-11, Department of Mathematics, NUS Speaker: Frank Stephan Title: Learning automatatic families of languages URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html A class of languages is automatic if it is uniformly regular using some regular index set for the languages. continue reading…

Frank Stephan: The complexity of semiautomatic structures

Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 21 October 2015, 17:00 hrs Room: S17#04-06, Department of Mathematics, NUS Speaker: Frank Stephan Title: The complexity of semiautomatic structures URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html Abstract: This talk extends previous work on semiautomatic structures and in particular investigates complexity issues with groups and semigroups; furthermore, results from recursion theory are used to show that one specific structure is not semiautomatic while a related one can be shown to be semiautomatic. continue reading…

Frank Stephan: Covering the Recursive Sets

Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 14 October 2015, 17:00 hrs Room: S17#04-06, Department of Mathematics, NUS Speaker: Frank Stephan Title: Covering the Recursive Sets URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html The talk gives an overview of recent work which solves two problems of Brendle, Brooke-Taylor, Ng and Nies. continue reading…

Frank Stephan: Covering the Recursive Sets

Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 19 August 2015, 17:00 hrs Room: S17#04-06, Department of Mathematics, NUS Speaker: Frank Stephan Title: Covering the Recursive Sets URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html The talk gives an overview of recent work which solves two problems of Brendle, Brooke-Taylor, Ng and Nies. continue reading…

Frank Stephan: Automatic Structures – recent results and open questions

Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 25 March 2015, 17:00 hrs Room: S17#05-11, Department of Mathematics, NUS Speaker: Frank Stephan Title: Automatic Structures – recent results and open questions URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html Abstract: Automatic structures are a way to represent algebraic structures using finite automata; all the algebraic operations and relations have to be recognised / verified by finite automata which read the inputs and outputs with the same speed (one symbol per cycle). continue reading…

Frank Stephan: Recent progress on partial learning and related notions

Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 14 January 2015, 17:00 hrs Room: S17#05-22, Department of Mathematics, NUS Speaker: Frank Stephan Title: Recent progress on partial learning and related notions. continue reading…

Frank Stephan: The complexity of verbal and pattern languages over groups

Invitation to the Logic Seminar at the National University of Singapore Date: Wednesday, 13 August 2014, 17:00 hrs Room: S17#04-05, Department of Mathematics, NUS Speaker: Frank Stephan Title: The complexity of verbal and pattern languages over groups URL: http://www.comp.nus.edu.sg/~fstephan/logicseminar.html Note: This meeting includes a short organisatorial session for organising the logic seminar in this semester; in the case that you want to speak but cannot come, please drop an email to Frank Stephan at fstephan@comp.nus.edu.sg. continue reading…

Frank Stephan: Closed left-r.e. sets

Invitation to the Logic Seminar at the National University of Singapore Please find below the invitation to the logic seminar. Note that we will also fix the timetable for the logic seminar in this semester in the first meeting; in the case that you want to speak but cannot come, please reply to this email with timings possible for you; you can consult the webpage of the seminar for possible time-slots. continue reading…