BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Drupal iCal API//EN
X-WR-CALNAME:Events items teaser
X-WR-TIMEZONE:America/Toronto
BEGIN:VTIMEZONE
TZID:America/Toronto
X-LIC-LOCATION:America/Toronto
BEGIN:DAYLIGHT
TZNAME:EDT
TZOFFSETFROM:-0500
TZOFFSETTO:-0400
DTSTART:20260308T070000
END:DAYLIGHT
BEGIN:STANDARD
TZNAME:EST
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
DTSTART:20251102T060000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
UID:69cf3e25e5ca3
DTSTART;TZID=America/Toronto:20260410T103000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260410T113000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/crypto-readi
 ng-group-elnaz-hessami-pilehrood-shadowfax
SUMMARY:Crypto Reading Group - Elnaz Hessami Pilehrood-Shadowfax: Hybrid\nS
 ecurity and Deniability for AKEMs
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n\n Elnaz Hessami Pilehrood\n\nAFFILIATION:\n Universi
 ty of Waterloo\n\nLOCATION:\n MC 6029\n\nABSTRACT:As cryptographic protoco
 ls transition to post-quantum\nsecurity\, most adopt hybrid solutions comb
 ining classical and\npost-quantum assumptions. This shift often sacrifices
  efficiency\,\ncompactness\, or even security. One such property is deniab
 ility\, which\nenables users to plausibly deny authorship of potentially\n
 incriminating messages. While classical protocols like X3DH key\nagreement
  (used in Signal and WhatsApp) provide deniability\,\npost-quantum protoco
 ls like PQXDH and Apple’s iMessage with PQ3 do\nnot. This work addresses
  this gap by investigating how to efficiently\npreserve deniability in pos
 t-quantum protocols. Specifically\, we\npropose two hybrid schemes for aut
 henticated key encapsulation\nmechanisms (AKEMs). The first is a black-box
  construction that\npreserves deniability when both constituent AKEMs are 
 deniable. The\nsecond is Shadowfax\, a non-black-box AKEM that achieves hy
 brid\nsecurity\, integrating a classical non-interactive key exchange\, a\
 npost-quantum key encapsulation mechanism\, and a post-quantum ring\nsigna
 ture. Shadowfax satisfies deniability in both dishonest and\nhonest receiv
 er settings\, relying on statistical security in the\nformer and on a sing
 le pre- or post-quantum assumption in the latter.\nFinally\, we provide se
 veral portable implementations of Shadowfax.\nWhen instantiated with stand
 ardised components (ML–KEM and Falcon)\,\nShadowfax yields ciphertexts o
 f 1 728 bytes and public keys of 2 036\nbytes\, with encapsulation and dec
 apsulation costs of 1.8M and 0.7M\ncycles on an Apple M1 Pro.
DTSTAMP:20260403T041221Z
END:VEVENT
BEGIN:VEVENT
UID:69cf3e25e94db
DTSTART;TZID=America/Toronto:20260406T144500
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260406T154500
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/graphs-and-m
 atroids-eileen-robinson-coloring-claw-free
SUMMARY:Graphs and Matroids - Eileen Robinson-Coloring claw-free graphs of\
 nbounded codegree
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Eileen Robinson\n\nAFFILIATION:\n Université libre 
 de Bruxelles\n\nROOM:\n MC 5479\n\nABSTRACT:We define the codegree of a gi
 ven graph as the maximum number\nof neighbors that any two distinct vertic
 es have in common.\n\nIn 2002\, V. Vu proposed that for a given graph\, it
 s chromatic number\nshould never be too much larger than its codegree\, pr
 ovided that its\ncodegree is not too small as a proportion of its maximum 
 degree.
DTSTAMP:20260403T041221Z
END:VEVENT
BEGIN:VEVENT
UID:69cf3e25ea123
DTSTART;TZID=America/Toronto:20260407T143000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260407T153000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-an
 d-enumerative-combinatorics-seminar-ashleigh
SUMMARY:Algebraic and enumerative combinatorics seminar-Ashleigh\nAdams-Pro
 motion\, plane partitions\, partial evaluations\, and webs
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Ashleigh Adams\n\nAFFILIATION:\n North Dakota State 
 University\n\nLOCATION:\n MC 6029\n\nABSTRACT: Webs are graphical objects
  that give a tangible\,\ncombinatorial way to compute and classify tensor 
 invariants. Recently\,\nGaetz\, Pechenik\, Pfannerer\, Striker\, and Swans
 on (arXiv:2306.12501)\nfound a rotation-invariant web basis for SL₄\, as
  well as its quantum\ndeformation U_q(sl₄)\, and a bijection between mov
 e equivalence\nclasses of SL₄-webs and fluctuating tableaux such that we
 b rotation\ncorresponds to tableau promotion. They also found a bijection 
 between\nthe set of plane partitions in an a×b×c box and a benzene move\
 nequivalence class of SL₄-webs by determining the corresponding\noscilla
 ting tableau. In this talk\, I will similarly find the\noscillating tablea
 ux corresponding to plane partitions in certain\nsymmetry classes by chara
 cterizing them via certain lattice words. A\ndynamical action on tableaux\
 , called promotion\, corresponds to\nrotation of SL₄-webs. I will show h
 ow promotion of certain\nsubtableaux aligns with rotation of their respect
 ive webs. I will also\nshow that this correspondence maps through a projec
 tion to either\nSL₂ or SL₃ webs. Moreover\, this projection is exactly
  a partial\nevaluation of webs. This talk will be given through the lens o
 f the\ncombinatorics of webs and tableaux. Some of this work is joint with
 \nJessica Striker.\n\nTHERE WILL BE A PRE-SEMINAR PRESENTING RELEVANT BAC
 KGROUND AT THE\nBEGINNING GRADUATE LEVEL STARTING AT 1:30PM.
DTSTAMP:20260403T041221Z
END:VEVENT
BEGIN:VEVENT
UID:69cf3e25eabad
DTSTART;TZID=America/Toronto:20260330T123000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260330T133000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/co-reading-g
 roup-jacob-skitsko-simple-proof-hardness-matrix
SUMMARY:C&O Reading Group - Jacob Skitsko-A Simple Proof of Hardness of Mat
 rix\nCompletion
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n\n Jacob Skitsko\n\nAFFILIATION:\n University of Wate
 rloo\n\nLOCATION:\n MC 6029\n\nABSTRACT:\n\nIn the matrix completion probl
 em\, we are given an incomplete matrix A\nas input. Some entries are fille
 d in\, and some entries have the value\n\"*\". Our task is to fill in the 
 \"*\" entries so that the resulting\ncompleted matrix has minimum rank. We
 'll discuss a simple proof from\nShitov showing that it is hard to disting
 uish between an incomplete\nmatrix having a rank 3 completion\, or all com
 pletions requiring at\nleast rank 4. \nThe idea is to index the matrix by 
 vectors. These vectors will\nrepresent a circuit computing a family of pol
 ynomials\, f(x) in F. The\nhope is that any rank 3 completion will be forc
 ed to fill in the\nmatrix values according to these vector labels. Thus\, 
 the completion\nwill specify values for x_i\, x_j\, x_i + x_j\, x_i * x_j\
 , ... \, and so\non until it specifies values for our polynomials f(x). If
  we force the\nf(x) in F entries to be 0\, then this is exactly a solution
  to the\npolynomial system F. Seeing why any rank 3 completion should be f
 orced\nto operate in this way takes a bit of squinting\, but is overall qu
 ite\npleasant.
DTSTAMP:20260403T041221Z
END:VEVENT
BEGIN:VEVENT
UID:69cf3e25eb65e
DTSTART;TZID=America/Toronto:20260402T143000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260402T153000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-an
 d-enumerative-combinatorics-seminar-hadleigh
SUMMARY:Algebraic and enumerative combinatorics seminar - Hadleigh\nFrost-N
 ested nestings\, Moment-Cumulant relations and the Combinatorics\nof the C
 osmos
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Hadleigh Frost\n\nAFFILIATION:\n Institute for Advan
 ced Study\n\nLOCATION:\n MC 5417\n\nABSTRACT: Cosmological correlation fu
 nctions probe the quantum\norigins of structure in the universe and are a 
 prototype for many\ncalculations in physics. I will share recent work on t
 he complexes\,\nfans and polytopes associated to these functions based on\
 narXiv:2602.21194 and ongoing work. Two structures lie at the heart of\nth
 is story: (1) incidence relations between chains and anti-chains\,\n(2) a 
 notion of \"nested sets of nested sets\". Both structures can be\nstudied 
 for an arbitrary lattice\, but building sets of the boolean\nlattice are m
 y main motivation.\n\nTHERE WILL BE A PRE-SEMINAR PRESENTING RELEVANT BAC
 KGROUND AT THE\nBEGINNING GRADUATE LEVEL STARTING AT 1:30PM.
DTSTAMP:20260403T041221Z
END:VEVENT
BEGIN:VEVENT
UID:69cf3e25ec103
DTSTART;TZID=America/Toronto:20260330T144500
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260330T154500
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/graphs-and-m
 atroids-lise-turner-anemones-and-matroids-high
SUMMARY:Graphs and Matroids - Lise Turner-Anemones and Matroids of High\nBr
 anch-Depth
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Lise Turner\n\nAFFILIATION:\n University of Waterloo
 \n\nROOM:\n MC 5479\n\nABSTRACT:We prove a conjecture by DeVos\, Kwon and 
 Oum on the\nunavoidable minors of matroids of high branch-depth. We also c
 onsider\nthe properties of collections of crossing low order separations k
 nown\nas anemones. This is joint work with Jim Geelen and Rutger Cambell.
DTSTAMP:20260403T041221Z
END:VEVENT
BEGIN:VEVENT
UID:69cf3e25ecac3
DTSTART;TZID=America/Toronto:20260327T153000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260327T163000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/tutte-colloq
 uium-therese-biedl-planar-graph-drawing-meet
SUMMARY:Tutte Colloquium -Therese Biedl-Planar graph drawing\, meet MSOL
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Therese Biedl\n\nAFFILIATION:\n University of Waterl
 oo\n\nLOCATION:\n MC 5501\n\nABSTRACT: It is well-known that every planar
  graph has a planar\ndrawing with straight-line segments\, even if vertice
 s are restricted\nto lie on a grid with linear coordinates.  In this talk
 \, we will\nstudy the question of finding planar graph drawings where the 
 height H\nof the grid is as small as possible.   Dujmovic et al gave an\n
 FPT-algorithm that finds the minimum height.  However\, it is not\npartic
 ularly adaptable to closely related problems\, such as finding\nrectilinea
 r drawings of minimum height.    We therefore study a new\nand completel
 y different approach to test whether a graph has a\ndrawing of height H. 
     Since such graphs have pathwidth O(H)\, a\nnatural approach is to ap
 peal to Courcelle's theorem.  This requires\nphrasing the problem in so-c
 alled monadic second-order logic (MSOL)\,\nbut MSOL supports neither arbit
 rarily large integers nor permutations\,\nmaking it difficult to use for g
 raph drawing problems.   In this\ntalk\, we show that with some detours w
 e can phrase the question of\nwhether G has a straight-line drawing of hei
 ght H in a radically\ndifferent way (\"no face has a fish\") that can be e
 asily expressed in\nMSOL.\n\n(Joint work with Ignaz Rutter)
DTSTAMP:20260403T041221Z
END:VEVENT
BEGIN:VEVENT
UID:69cf3e25ed47b
DTSTART;TZID=America/Toronto:20260327T103000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260327T113000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/crypto-readi
 ng-group-mohammad-hajiabadi-challenges-realizing
SUMMARY:Crypto Reading Group - Mohammad Hajiabadi-Challenges in Realizing C
 CA\nin Advanced Encryption Schemes
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n\n Mohammad Hajiabadi\n\nAFFILIATION:\n University of
  Waterloo\n\nLOCATION:\n MC 6029\n\nABSTRACT:CCA security is a fundamental
  notion in cryptography. There\nare standard techniques to generically ach
 ieve CCA security for\nall-or-nothing type public-key encryption schemes\,
  such as heuristic\napproaches based on Fujisaki–Okamoto\, or constructi
 ons in the\nstandard model using tools like hinting PRGs. However\, in mor
 e\nadvanced settings\, such as functional encryption or threshold\nencrypt
 ion\, these generic approaches break down. Moreover\, defining\nCCA securi
 ty in these settings is itself non-trivial and leads to\nsubtle definition
 al challenges.\n\nIn this talk\, I will discuss these issues\, highlight t
 he key\nobstacles\, and present several open problems\, along with possibl
 e\ndirections for addressing them.
DTSTAMP:20260403T041221Z
END:VEVENT
BEGIN:VEVENT
UID:69cf3e25edef5
DTSTART;TZID=America/Toronto:20260326T143000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260326T153000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-an
 d-enumerative-combinatorics-seminar-ian-george
SUMMARY:Algebraic and enumerative combinatorics seminar - Ian\nGeorge-Enume
 rating Convex Sets in Posets
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Ian George\n\nAFFILIATION:\n University of Waterloo\
 n\nLOCATION:\n MC 5417\n\nABSTRACT: Causal Set Theory (CST) is a theory o
 f quantum gravity\nwhere spacetime is taken to be a locally finite poset\,
  called a causal\nset.  A central problem in CST is to determine physical
 ly relevant\nproperties from the purely combinatorial information of the c
 ausal\nset.  In 2014 Glaser and Surya demonstrated that the distribution 
 of\ninterval sizes of a causal set sprinkled into a region of Minkowski\ns
 pace contains information about the dimension of the underlying\nspacetime
 .  In 2026 Surya showed that this distribution can be used\nto define a 
 “closeness” function on causal sets that distinguishes\nby dimension a
 nd global topology.  In this talk we present work\nmotivated by these res
 ults which investigates the more general notion\nof convex sets\, instead 
 of intervals\, of a poset.  First\, we will\nintroduce a generating polyn
 omial for convex sets in a finite poset\nand explore some of its propertie
 s.  We will then show that this\npolynomial is a complete invariant for t
 he family of series-parallel\nposets.  Lastly\, we discuss early results 
 on the utility of this\npolynomial in CST.  The pre-seminar will introduc
 e relevant\nbackground on CST.\n\nTHERE WILL BE A PRE-SEMINAR PRESENTING 
 RELEVANT BACKGROUND AT THE\nBEGINNING GRADUATE LEVEL STARTING AT 1:30PM.
DTSTAMP:20260403T041221Z
END:VEVENT
BEGIN:VEVENT
UID:69cf3e25ee939
DTSTART;TZID=America/Toronto:20260323T113000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260323T123000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-gr
 aph-theory-zhaochen-ding-construction
SUMMARY:Algebraic Graph Theory-Zhaochen Ding-A construction of multicovers 
 of\na cycle
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Zhaochen Ding\n\nAFFILIATION: \n\nUniversity of Prim
 orska\n\nLOCATION:\n Please contact Sabrina Lato for Zoom link.\n\nABSTR
 ACT: Praeger-Xu graphs are a family of multicovers of cycles\,\nknown for
  some of their surprising properties. A fundamental\nobservation is that t
 hese graphs can be constructed from De Bruijn\ngraphs. In this presentatio
 n\, we will generalize the definition of De\nBruijn graphs to create a bro
 ader family of multicovers. Finally\, we\nwill compute the automorphism gr
 oup and show some applications of our\nconstructions. This is a joint work
  with Ci Xuan Wu.
DTSTAMP:20260403T041221Z
END:VEVENT
END:VCALENDAR