Marcin Wrochna – personal web page

Postdoc (December 2018-2020)

Department of Computer Science
University of Oxford
Power of Algorithms in Discrete Optimisation

PhD student (2014–2018)

Faculty of Mathematics, Informatics and Mechanics
University of Warsaw
Thesis: The topology of solution spaces of combinatorial problems
Advisor: Michał Pilipczuk

Masters (2012–2014)

Computer Science
Faculty of Mathematics, Informatics and Mechanics
University of Warsaw
Thesis: Reconfiguration and structural graph theory
Advisor: Marcin Kamiński

Bachelors (2009–2012)

Computer Science + Physics (advanced track)
College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences
University of Warsaw
Full CV

Marcin Wrochna

My interests range over theoretical aspects of computer science, focusing on parameterized algorithms, graph theory, computational complexity and occasionally logic. Currently I am looking into connections to more applied algorithmics.

My PhD thesis investigates multiplicative graphs, which are the subject of Hedetniemi's conjecture (on coloring graph products), as well as spaces of graph homomorphisms, using new algebraic-topological methods. News: in May 2019, Hedetniemi's conjecture was refuted by Yaroslav Shitov!

Publications

2020

• Sallow – a heuristic algorithm for treedepth decompositions  GitHub | a submission for PACE 2020
• Topology and adjunction in promise constraint satisfaction
  with Andrei Krokhin, Jakub Opršal, Stanislav Živný
    submitted | merge of arXiv:1904.03214 and Improved hardness for H-colourings…. Theorem 4.17 is improved from 4- to 3-colourings. Adjunction is discussed in the context of gadget constructions. The proofs are significantly more detailed and the presentation has been overhauled, with more examples.

2019

• The power of the combined basic LP and affine relaxation for promise CSPs
  with Joshua Brakensiek, Venkatesan Guruswami, Stanislav Živný
    submitted | extends SODA 2020 paper by Joshua Brakensiek and Venkatesan Guruswami
• The complexity of promise SAT on non-Boolean domains
  with Alex Brandts, Stanislav Živný
    ICALP 2020 | presentation on YouTube
• Treewidth-Pliability and PTAS for Max-CSPs
  with Miguel Romero, Stanislav Živný
    submitted
• Improved hardness for H-colourings of G-colourable graphs
  with Stanislav Živný
    SODA 2020 | contains small results about category theory not included in Topology and adjunction…

2018

• Graphs that are not strongly multplicative
  with Claude Tardif
    in preparation…
• Tight complexity lower bounds for integer linear programming with few constraints
  with Dušan Knop, Michał Pilipczuk
    STACS 2019 | ACM TOCT
• Integer Programming and Incidence Treedepth
  with Eduard Eiben, Robert Ganian, Dušan Knop, Sebastian Ordyniak, Michał Pilipczuk
    IPCO 2019
• Hedetniemi's conjecture and strongly multiplicative graphs
  with Claude Tardif
    SIAM J. Discrete Math.
• The step Sidorenko property and non-norming edge-transitive graphs
  with Daniel Král’, Taísa L. Martins, Péter Pál Pach
    J. Comb. Theory A (JCTA)

2017

• On inverse powers of graphs and topological implications of Hedetniemi's conjecture  | J. Comb. Theory B (JCTB)
• Turing kernelization for finding long paths in graph classes excluding a topological minor
  with Bart M. P. Jansen, Marcin Pilipczuk
    IPEC 2017 | invited to Algorithmica special issue
• On Directed Feedback Vertex Set parameterized by treewidth
  with Marthe Bonamy, Łukasz Kowalik, Jesper Nederlof, Michał Pilipczuk, Arkadiusz Socała
    WG 2018

2016

• Tight lower bounds for the complexity of multicoloring
  with Marthe Bonamy, Łukasz Kowalik, Michał Pilipczuk, Arkadiusz Socała
    ESA 2017 | ACM Trans. Comput. Theory (TOCT)
• Cutwidth: obstructions and algorithmic aspects
  with Archontia C. Giannopoulou, Michał Pilipczuk, Jean-Florent Raymond, Dimitrios M. Thilikos
    IPEC 2016, Best Paper award | invited to Algorithmica special issue
• Linear kernels for edge deletion problems to immersion-closed graph classes
  with Archontia C. Giannopoulou, Michał Pilipczuk, Jean-Florent Raymond, Dimitrios M. Thilikos
    ICALP 2017
• Square-free graphs are multiplicative  SIAM DM 2016 | J. Comb. Theory B (JCTB)
    presentation | Young Author Prize at Bordeaux Graph Workshop

2015

• Fully polynomial-time parameterized computations for graphs and matrices of low treewidth
  with Fedor V. Fomin, Daniel Lokshtanov, Michał Pilipczuk, Saket Saurabh
    SODA 2017 | ACM Trans. Algorithms (TALG)
• On space efficiency of algorithms working on structural decompositions of graphs
  with Michał Pilipczuk
    STACS 2016 | ACM Trans. Comput. Theory (TOCT)
• Edge bipartization faster than 2^k
  with Marcin Pilipczuk, Michał Pilipczuk
    IPEC 2016 | invited to Algorithmica special issue
• Polynomial kernelization for removing induced claws and diamonds
  with Marek Cygan, Marcin Pilipczuk, Michał Pilipczuk, Erik Jan van Leeuwen
    WG 2015 | Theory Comput. Syst. (ToCS)

2014

• Homomorphism reconfiguration via homotopy  SIAM J. Discrete Math. | STACS 2015 | animated presentation (fr)
• Reconfiguration in bounded bandwidth and treedepth  J. Comput. Syst. Sci. | slides | (abridged version in joint paper below)
• Reconfiguration over tree decompositions
  with Amer E. Mouawad, Naomi Nishimura, Venkatesh Raman
    IPEC 2014
• Reconfiguring independent sets in claw-free graphs
  with Paul Bonsma, Marcin Kamiński
    SWAT 2014 | slides

Activities

• Principal investigator in The topology of solution spaces of combinatorial problems, a PRELUDIUM grant funded by the National Science Centre, Poland (2017-2019).
• Research project CUTACOMBS with Marcin Pilipczuk.
• Research project Optimality in parameterized complexity with my advisor Michał Pilipczuk (2014-2017).
• I visited Daniel Kráľ at the University of Warwick, DIMAP, for 5 weeks in 2017; Claude Tardif at Queen's University in Kingston, Ontario, for a week in 2017; Marthe Bonamy at LaBRI, Bordeaux, for 2 weeks in 2016; the Bergen Algorithms Research Group for a week in 2015 and two weeks in 2016.
• Second award for best master thesis in computer science in Poland, from PTI.
• Research project Graphs Within Graphs with my masters' advisor Marcin Kamiński (2013-2014).
• I visited the University of Waterloo, Canada for 2 weeks for a research collaboration with Naomi Nishimura and Amer Mouawad (2014).

* pronounced [ˈmarʨ̑in 'vrɔxna], like "mar-chin vroh-na", but "Martin" is perfectly fine :)