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TZID:America/Toronto
X-LIC-LOCATION:America/Toronto
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TZOFFSETFROM:-0500
TZOFFSETTO:-0400
DTSTART:20260308T070000
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TZNAME:EST
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
DTSTART:20251102T060000
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BEGIN:VEVENT
UID:6a226f841d34e
DTSTART;TZID=America/Toronto:20260618T143000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260618T153000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-an
 d-enumerative-combinatorics-seminar-scott
SUMMARY:Algebraic and Enumerative combinatorics seminar -Scott\nNeville-Eve
 ntual sign coherence
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Scott Neville\n\nAFFILIATION:\n LACIM\n\nLOCATION:\n
  MC 6460\n\nABSTRACT: The sign coherence of c-vectors is one of the funda
 mental\ntheorems of cluster algebras with principal coefficients.  Gekhtm
 an\nand Nakanishi posed the Asymptotic Sign Coherence Conjecture for\nclus
 ter algebras with arbitrary coefficients\, which says sign\ncoherence shou
 ld eventually hold in any sufficiently generic infinite\nmutation sequence
 .  We prove that for cluster algebras from quivers\nof arbitrary rank\, t
 heir conjecture holds with probability 1 for a\nrandom mutation sequence.
   Our results also establish the conjecture\nin full generality for many 
 families of quivers.  This is joint work\nwith Amanda Burcroff.\n\nTHERE 
 WILL BE A PRE-SEMINAR PRESENTING RELEVANT BACKGROUND AT\nBEGINNING GRADUAT
 E LEVEL STARTING AT 1:30PM IN MC 5417.
DTSTAMP:20260605T064108Z
END:VEVENT
BEGIN:VEVENT
UID:6a226f841e390
DTSTART;TZID=America/Toronto:20260612T153000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260612T163000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/tutte-colloq
 uium-douglas-stebila-adding-functionality-post
SUMMARY:Tutte Colloquium -Douglas Stebila-Adding functionality to post-quan
 tum\ncryptography with variants of the Fujisaki-Okamoto transform
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Douglas Stebila\n\nAFFILIATION:\n University of Wate
 rloo\n\nLOCATION:\n MC 5501\n\nABSTRACT: The Fujisaki-Okamoto (FO) transf
 orm is a fundamental\nbuilding block in new post-quantum cryptography stan
 dards like NIST's\nML-KEM\, where it is used to convert a weakly secure pu
 blic key\nencryption scheme into a key encapsulation mechanism (KEM) secur
 e\nagainst active attackers. In this talk\, we'll explore two approaches\n
 to add extra security and functionality to post-quantum KEMs by\nenhancing
  the FO transform. First\, we see how a birthday-style\ncollision argument
  lets an attacker who collects many ciphertexts\nhalve the security of the
  FrodoKEM and HQC standards\, and how\nextending the FO transform with pub
 lic salts thwarts this multi-target\nattack. Second\, we turn to implement
 ation flaws: for 19 months\, HQC's\nreference implementation effectively s
 kipped a security-critical\nverification step\, yet basic correctness test
 s still passed. We show\nhow the principle of \"verifiable verification\"\
 , via an extension of\nthe FO transform\, ties security to functionality\,
  so that an\nimplementation which that skips it visibly breaks.
DTSTAMP:20260605T064108Z
END:VEVENT
BEGIN:VEVENT
UID:6a226f841ebbe
DTSTART;TZID=America/Toronto:20260612T103000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260612T113000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/crypto-readi
 ng-group-camryn-steckel-decoding-quasi-cyclic
SUMMARY:Crypto Reading Group - Camryn Steckel-Decoding for Quasi-Cyclic Cod
 es
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n\n Camryn Steckel\n\nAFFILIATION:\n University of Wat
 erloo\n\nLOCATION:\n MC 5417\n\nABSTRACT:\n\nThis session focuses on deco
 ding questions specific to quasi-cyclic\ncodes. We will discuss syndrome d
 ecoding in the quasi-cyclic setting\nand compare generic ISD methods with 
 approaches that exploit\nadditional structure. The goal is to better under
 stand the tension\nbetween efficiency and security\, and to prepare the gr
 ound for the\nstudy of the HQC scheme. \nReferences: [§6.3\, 4]\, [§3\, 
 6]\, and [§5\, 10] \n[4] HQC Team. Hamming Quasi-Cyclic (HQC)\, NIST Subm
 ission\, 2025. \n[6] C. Löndahl\, T. Johansson\, M. Koochak Shooshtari\, 
 M.\nAhmadian-Attari\, and M. Reza Aref. Squaring attacks on McEliece\npubl
 ic-key cryptosystems using quasi-cyclic codes of even dimension.\nDesigns\
 , Codes and Cryptography \, vol. 80\, pp. 359–377\, 2016. \n[10] N. Send
 rier. Decoding One Out of Many. Post-Quantum Cryptography.\nPQCrypto 2011.
  Lecture Notes in Computer Science\, vol. 7071\, Springer\,\n2011. \nA wee
 k-by-week plan is outlined at the following\nlink: https://www.leonardoco
 lo.com/seminars/Spring26.html.
DTSTAMP:20260605T064108Z
END:VEVENT
BEGIN:VEVENT
UID:6a226f841f4f0
DTSTART;TZID=America/Toronto:20260611T143000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260611T153000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-an
 d-enumerative-combinatorics-seminar-kevin
SUMMARY:Algebraic and Enumerative combinatorics seminar - Kevin Purbhoo- Th
 e\nhook length formula massacree
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Kevin Purbhoo\n\nAFFILIATION:\n University of Waterl
 oo\n\nLOCATION:\n MC 6460\n\nABSTRACT: Around 1900 Young and Frobenius (i
 ndependently\, and through\nvery different techniques) obtained a formula 
 for the dimensions of\nthe irreducible representations of the symmetric gr
 oup. Some 53 years\nlater\, Frame\, Robinson and Thrall noticed that the Y
 oung-Frobenius\nformula simplified into the now famous hook length formula
 . Nowadays\nthere are many proofs\, but the hook length formula remains so
 mething\nof a mystery\, as if some deeper understanding lies just out of r
 each.\nOne aspect of this mystery is that none of the proofs seem to indic
 ate\nhow one might come up with the formula in the first place\, other tha
 n\njust guessing.\n\nI will attempt to answer that question. It is an impr
 obable tale that\nmeanders through scenes of Young symmetrizers\, Schur-We
 yl duality\,\nWeyl algebras\, elementary combinatorics\, and Plücker rela
 tions. All\nbecause Google's AI gave me a very obviously wrong answer when
  I was\ntrying to find out the square of a Young symmetrizer.\n\nTHERE WIL
 L BE A PRE-SEMINAR PRESENTING RELEVANT BACKGROUND AT\nBEGINNING GRADUATE L
 EVEL STARTING AT 1:30PM IN MC 5417.
DTSTAMP:20260605T064108Z
END:VEVENT
BEGIN:VEVENT
UID:6a226f841fcd8
DTSTART;TZID=America/Toronto:20260605T123000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260605T133000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/combopt-read
 inggroup-david-aleman-unsplittable
SUMMARY:CombOpt ReadingGroup - David Aleman-Unsplittable multicommodity flo
 ws\nin fully planar instances
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n\n David Aleman\n\nAFFILIATION:\n University of Water
 loo\n\nLOCATION:\n MC 6029\n\nABSTRACT: \n\nThe multicommodity flow probl
 em involves routing multiple distinct\ncommodities through a shared networ
 k. An instance is given by\nan _undirected _graph G=(V\, E(G) ) with ed
 ge capacities\, and a\ncollection of source-sink pairs (s_i\,t_i) in V wit
 h associated\nnonnegative demands d(s_i\, t_i). It will be convenient to t
 hink of the\nsource-sink pairs as forming the edges of a demand graph H=( 
 V\, E(H)\n). A flow is _feasible_ if it routes all demands without excee
 ding\nthe edge capacities\, and it is _unsplittable_ if it routes each\n
 demand along a single path. Let C be the smallest value such that the\nexi
 stence of a feasible flow implies the existence of an unsplittable\nflow t
 hat exceeds the edge capacities by at most an additivie amount\nof C times
  the maximum demand value.  \nWe show that if G+H = (V\, E(G) U E(H) ) is
  planar\, then  1.5<= C <=\n2. \nJoint work with Kumar\, Poremba\, and Sh
 epherd. 
DTSTAMP:20260605T064108Z
END:VEVENT
BEGIN:VEVENT
UID:6a226f84204a5
DTSTART;TZID=America/Toronto:20260601T140000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260601T150000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/crypto-readi
 ng-group-roman-langrehr-sam-jaques-information
SUMMARY:Crypto Reading Group - Roman Langrehr & Sam Jaques-Information Set
 \nDecoding
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n\n Roman Langrehr & Sam Jaques\n\nAFFILIATION:\n Uni
 versity of Waterloo\n\nLOCATION:\n MC 6483\n\nABSTRACT:\n\nIn this session
 \, we study information set decoding (ISD)\, one of the\nmain generic appr
 oaches for attacking code-based cryptosystems. We\nwill present the basic 
 ideas behind Prange's algorithm and Stern's\nalgorithm\, together with the
  general philosophy of decoding attacks in\nthe random-code setting. The a
 im is to understand both the algorithmic\nframework and its importance in 
 concrete security estimates.
DTSTAMP:20260605T064108Z
END:VEVENT
BEGIN:VEVENT
UID:6a226f8420bcd
DTSTART;TZID=America/Toronto:20260529T103000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260529T113000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/crypto-readi
 ng-group-pranshu-kumar-john-premkumar-karaneh
SUMMARY:Crypto Reading Group - Pranshu Kumar & John Premkumar & Karaneh\nKe
 ypoor-Quasi-Cyclic Codes
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n\n Pranshu Kumar & John Premkumar & Karaneh Keypoor\n
 \nAFFILIATION:\n University of Waterloo\n\nLOCATION:\n MC 5417\n\nABSTRAC
 T:\n\nThis session is devoted to quasi-cyclic codes\, one of the main\nstr
 uctured code families used in modern code-based cryptography. We\nwill int
 roduce their definition and main properties\, and explain why\ntheir addit
 ional algebraic structure is both useful for efficiency and\ndelicate from
  a security perspective. This week will provide the\nbackground needed to 
 understand HQC and related constructions.
DTSTAMP:20260605T064108Z
END:VEVENT
BEGIN:VEVENT
UID:6a226f8421366
DTSTART;TZID=America/Toronto:20260605T153000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260605T163000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/tutte-colloq
 uium-david-gosset-triply-efficient-shadow
SUMMARY:Tutte Colloquium -David Gosset-Triply efficient shadow tomography
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n David Gosset\n\nAFFILIATION:\n University of Waterlo
 o\n\nLOCATION:\n MC 5501\n\nABSTRACT:  Given copies of a quantum state\,
  a shadow tomography\nprotocol aims to learn all expectation values from a
  fixed set of\nobservables\, to within a given precision. We say that such
  a protocol\nis triply efficient if it is sample efficient\, time efficien
 t\, and\nuses measurements that entangle a constant number of copies of th
 e\nstate at a time.   A natural family of shadow tomography protocols\nb
 ased on random single-copy Clifford measurements can be understood as\nari
 sing from fractional colorings of a graph G that encodes the\ncommutation 
 structure of the set of observables. Here we describe a\nframework for two
 -copy shadow tomography that uses an initial round of\nBell measurements t
 o reduce to a fractional coloring problem in an\ninduced subgraph of G wi
 th bounded clique number. This coloring\nproblem can be addressed using te
 chniques from graph theory known as\nchi-boundedness. Using this framework
  we give the first triply\nefficient  shadow tomography scheme for the se
 t of local fermionic\nobservables\, which arise in a broad class of intera
 cting fermionic\nsystems in physics and chemistry. We also give a triply e
 fficient\nscheme for the set of all -qubit Pauli observables. Our protocol
 s for\nthese tasks use two-copy measurements\, which is necessary:\nsample
 -efficient schemes are provably impossible using only\nsingle-copy measure
 ments. This is joint work with Robbie King\, Robin\nKothari\, and Ryan Bab
 bush.
DTSTAMP:20260605T064108Z
END:VEVENT
BEGIN:VEVENT
UID:6a226f8421aa7
DTSTART;TZID=America/Toronto:20260604T143000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260604T153000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-an
 d-enumerative-combinatorics-seminar-theodore
SUMMARY:Algebraic and Enumerative combinatorics seminar - Theodore\nMorriso
 n-Satisfiability thresholds of linear equations over a\ncommutative ring
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Theodore Morrison\n\nAFFILIATION:\n University of Wa
 terloo\n\nLOCATION:\n MC 6460\n\nABSTRACT:The satisfiability threshold of 
 a random constraint\nsatisfaction problem (CSP) is the density of constrai
 nts at which a\nrandom CSP instance transitions from being satisfiable to\
 nunsatisfiable with high probability. Much of the research on well\nknown 
 CSPs\, including the $k$-SAT problem\, $k$-XORSAT problem\,\nhypergraph co
 louring\, and systems of linear equations\, has focused on\ndetermining sa
 tisfiability thresholds.\n\nIn this talk we consider systems of linear equ
 ations over finite\ncommutative rings as CSPs\, and build on the work of A
 yre\, Coja-Oghlan\,\nGao\, and Müller\, who determined the satisfiability
  threshold for\nrandom linear equations over a finite field. We determine 
 when the\nsatisfiability threshold is linear in the number of variables\, 
 and\nshow that any linear threshold over a principal ideal ring coincides\
 nwith the (unique) linear threshold over fields. We also determine the\nsa
 tisfiability threshold for some examples of non-principal ideal\nrings.\n\
 nThis is joint work with Jane Gao.\n\nTHERE WILL BE A PRE-SEMINAR PRESENTI
 NG RELEVANT BACKGROUND AT\nBEGINNING GRADUATE LEVEL STARTING AT 1:30PM IN 
 MC 5417.
DTSTAMP:20260605T064108Z
END:VEVENT
BEGIN:VEVENT
UID:6a226f84222e3
DTSTART;TZID=America/Toronto:20260525T150000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20260525T160000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/graphs-and-m
 atroids-stephen-arndt-approximation-algorithms
SUMMARY:Graphs and Matroids - Stephen Arndt-Approximation Algorithms for\nM
 atroid-Intersection Coloring with Applications to Rota's Basis\nConjecture
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Stephen Arndt\n\nAFFILIATION:\n Carnegie Mellon Univ
 ersity\n\nROOM:\n MC 5417\n\nABSTRACT:We study algorithmic matroid interse
 ction coloring. We give\nthe first polynomial-time O(1)-approximation algo
 rithm to color O(1)\ngeneral matroids. Notably\, for two general matroids 
 we achieve a\n2-approximation. Furthermore\, we give a fully polynomial ra
 ndomized\napproximation scheme (FPRAS) for coloring the intersection of tw
 o\nmatroids when the maximum chromatic number is large. This yields the\nf
 irst polynomial-time algorithm for an asymptotic variant of Rota's\nBasis 
 Conjecture.
DTSTAMP:20260605T064108Z
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