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TZOFFSETFROM:-0500
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DTSTART:20260308T070000
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TZNAME:EST
TZOFFSETFROM:-0400
TZOFFSETTO:-0500
DTSTART:20251102T060000
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BEGIN:VEVENT
UID:6adaf9f2ce009
DTSTART;TZID=America/Toronto:20261026T150000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20261026T160000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/graphs-and-m
 atroids-hidde-koerts-faster-3-colouring
SUMMARY:Graphs and Matroids | Hidde Koerts\, Faster 3-colouring algorithm f
 or\ngraphs of diameter 3
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Hidde Koerts \n\nAFFILIATION:\n University of Water
 loo\n\nROOM:\n MC 6029\n\nABSTRACT: Determining whether a graph is k-colo
 urable is a famously\nhard computational problem. Even when placing signif
 icant restrictions\non the graph\, the resulting problem is often NP-hard.
  In this talk\,\nwe focus on the case of restricting the diameter. Under 
 the\nExponential Time Hypothesis\, there does not exist a sub-exponential\
 nalgorithm for 3-colouring diameter-4 graphs or for 4-colouring\ndiameter-
 2 graphs. Hence\, the interesting remaining cases are\n3-colouring graphs 
 of diameter 2 or 3. We show that 3-colouring\ndiameter-3 graphs can be so
 lved in 2^O(n^{2/3−ε}) for any ε < 1/33\nby providing an algorithm bas
 ed on a structural result. This improves\non the previous best known algor
 ithm due to Dębski\, Piecyk and\nRzążewski.\n\nThis talk is based on jo
 int work with Carla Groenland and Sophie\nSpirkl.
DTSTAMP:20261023T060850Z
END:VEVENT
BEGIN:VEVENT
UID:6adaf9f2d0a13
DTSTART;TZID=America/Toronto:20261028T100000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20261028T110000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/crypto-readi
 ng-group-quantum-computing-douglas-stebila-qkd
SUMMARY:Crypto Reading Group on quantum computing | Douglas Stebila\, QKD\n
 Security
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Douglas Stebila\n\nAFFILIATION:\n University of Wate
 rloo\n\nROOM:\n MC 5501\n\nABSTRACT: Having seen the BB84 quantum key dis
 tribution protocol last\nweek\, this week we’ll see what it means for QK
 D to be secure\,\nfollowing the basic principle that “information gain i
 mplies\ndisturbance”. We’ll talk about what authentication is needed f
 or\nQKD’s security guarantees to hold\, and other factors like device\ns
 ecurity and finite key effects.
DTSTAMP:20261023T060850Z
END:VEVENT
BEGIN:VEVENT
UID:6adaf9f2d1317
DTSTART;TZID=America/Toronto:20261029T143000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20261029T153000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-an
 d-enumerative-combinatorics-seminar-shao-yuan
SUMMARY:Algebraic and Enumerative Combinatorics Seminar | Shao Yuan Lin\,\n
 Distinguishability and linear independence for H-chromatic symmetric\nfunc
 tions
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Shao Yuan Lin\n\nAFFILIATION:\n University of Waterl
 oo\n\nLOCATION:\n MC 5417\n\nABSTRACT: We study the H-chromatic symmetric
  functions X_G^H\nintroduced by Eagles et al. (2022)\, which generalizes t
 he chromatic\nsymmetric function X_G to the context of H-colorings\, which
  tracks\ngraph homomorphisms G → H. We first show that self-chromatic\ns
 ymmetric functions X_G^G determine quantities like the connected\ncomponen
 ts of a forest and the degree sequence of a caterpillar. We\nthen show tha
 t the X_G^H's form a basis of the symmetric function ring\nfor certain col
 lections of (G\,H)\, such as the self-CSFs of complete\nmultipartite graph
 s. Lastly\, we define and discuss H-chromatic\npolynomials as specializati
 ons of H-CSFs. This is joint work with\nLaura Pierson.\n\nThere will be a 
 pre-seminar presenting relevant background at\nbeginning graduate level st
 arting at 1:30pm in MC 5417.
DTSTAMP:20261023T060850Z
END:VEVENT
BEGIN:VEVENT
UID:6adaf9f2d1b74
DTSTART;TZID=America/Toronto:20261019T150000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20261019T160000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/graphs-and-m
 atroids-emanuel-juliano-morais-silva-connection
SUMMARY:Graphs and Matroids | Emanuel Juliano Morais Silva\, On the connect
 ion\nbetween max-cuts\, the vector chromatic number\, and random sphere\ng
 raphs
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Emanuel Juliano Morais Silva\n\nAFFILIATION:\n Unive
 rsity of Waterloo\n\nROOM:\n MC 6029\n\nABSTRACT: It is well known that t
 he maximum cut size of a graph is at\nleast half its number of edges. But 
 how small can this difference be?\nUsing random hyperplane rounding\, a te
 chnique from semidefinite\noptimization\, Balla\, Janzer\, and Sudakov obt
 ained a lower bound on\nthis difference in terms of the vector chromatic n
 umber\, recovering\nknown extremal bounds for $C_r$-free graphs. I will pr
 esent their\nargument and show that the constant in their vector-chromatic
  bound is\noptimal by constructing a random sphere graph.
DTSTAMP:20261023T060850Z
END:VEVENT
BEGIN:VEVENT
UID:6adaf9f2d22a8
DTSTART;TZID=America/Toronto:20261021T100000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20261021T110000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/crypto-readi
 ng-group-quantum-computing-masuda-fatima-maggie
SUMMARY:Crypto Reading Group on quantum computing | Masuda Fatima & Maggie\
 nSimmons\, Quantum Key Distribution
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Masuda Fatima & Maggie Simmons\n\nAFFILIATION:\n Uni
 versity of Waterloo\n\nROOM:\n MC 5501\n\nABSTRACT: Quantum Key Distribut
 ion (QKD) uses the laws of Quantum\nMechanics to allow two parties to prod
 uce a shared secret key only\nknown to them without it's security relying 
 on the computational\nhardness. In this presentation\, we will introduce t
 he QKD protocol\nBB84\, and present how it is secure against various attac
 ks. We will\nalso discuss two major phases in BB84: the information reconc
 iliation\nphase between keys of sender and receiver via error correcting c
 odes\nand the privacy amplification phase where two communicating parties\
 ndistill highly secret shared key from a larger body of a shared key\,\nwh
 ich is only partially secret. Finally\, we will give a brief overview\nof 
 Muckle-based hybrid authenticated key exchange (AKE) protocols.
DTSTAMP:20261023T060850Z
END:VEVENT
BEGIN:VEVENT
UID:6adaf9f2d298e
DTSTART;TZID=America/Toronto:20261022T143000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20261022T153000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/algebraic-an
 d-enumerative-combinatorics-seminar-patty
SUMMARY:Algebraic and Enumerative Combinatorics Seminar | Patty Commins\,\n
 Signed combinatorics and the Mantaci–Reutenauer algebra
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Patty Commins\n\nAFFILIATION:\n Laboratoire d'Algèb
 re\, de Combinatoire et d'Informatique\nMathématique (LACIM)\n\nLOCATION:
 \n MC 5417\n\nABSTRACT: The Mantaci–Reutenauer algebra is a subalgebra 
 of the\ngroup algebra of signed permutations which has close ties to symme
 tric\nfunctions\, descents\, and characters. In this talk\, we explore its
 \nrepresentation theory and explain how it is governed by simple\noperatio
 ns on signed versions of classical combinatorial objects (i.e.\npartitions
 \, necklaces). This builds on a well-studied type A story for\nSolomon's \
 "descent algebra\". The representation-theoretic data we will\nconsider in
 clude the Cartan matrix\, the representation type\, and a\nconjectural Ext
 -quiver\; we will explain these notions during the talk.\nThis is ongoing 
 joint work with Alice Dell'Arciprete.\n\nTHERE WILL BE A PRE-SEMINAR PRESE
 NTING RELEVANT BACKGROUND AT THE\nBEGINNING GRADUATE LEVEL STARTING AT 1:
 30PM IN MC 5417.
DTSTAMP:20261023T060850Z
END:VEVENT
BEGIN:VEVENT
UID:6adaf9f2d30bb
DTSTART;TZID=America/Toronto:20261023T153000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20261023T163000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/tutte-colloq
 uium-sepehr-assadi-greedy-optimal-semi-streaming
SUMMARY:Tutte Colloquium | Sepehr Assadi\, Greedy is Optimal for the\nSemi-
 Streaming Matching Problem
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Sepehr Assadi\n\nAFFILIATION:\n University of Waterl
 oo\n\nLOCATION:\n MC 5501\n\nABSTRACT: We prove that no single-pass semi-s
 treaming algorithm\n(deterministic or randomized) can achieve a better-tha
 n-half\napproximation to the maximum matching problem. This implies the\no
 ptimality of the naive greedy algorithm\, answering a longstanding\nopen q
 uestion in graph streaming literature since the introduction of\nthe model
 . Our proof consists of two main parts:\n\n 1. Blueprint framework: reduc
 ing the problem of proving lower bounds\nfor semi-streaming matching to co
 nstructing certain combinatorial\nobjects which we call blueprints\; and\,
 \n\n 2. Blueprint construction: an optimal construction of such\nblueprin
 ts usable within this framework.\n\n Putting these two parts together imp
 lies our semi-streaming matching\nlower bound.\n\nBased on joint work with
  Max Jiang and Mars Xiang in\nhttps://arxiv.org/abs/2607.14644 (STOC 2026)
  and\nhttps://arxiv.org/abs/2607.14656 (arXiv\; July 2026)
DTSTAMP:20261023T060850Z
END:VEVENT
BEGIN:VEVENT
UID:6adaf9f2d384b
DTSTART;TZID=America/Toronto:20261005T110000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20261005T120000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/combopt-read
 ing-group-kanstantsin-pashkovich-nearly-tight
SUMMARY:CombOpt Reading Group | Kanstantsin Pashkovich\, Nearly Tight Upper
 \nBound for Matroid Intersection Prophet Inequality
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n\nKanstantsin Pashkovich\n\nAFFILIATION:\n University
  of Waterloo\n\nROOM:\n MC 6029\n\nABSTRACT: In this talk\, I will go ove
 r the construction that shows a\nlower bound of d/log(d) for the prophet i
 nequality\, where the feasible\nset is the intersection of d matroids. Thi
 s talk is based on the paper\n\"A Nearly Tight Lower Bound for Matroid Int
 ersection Prophet\nInequalities\" by Dimitris Fotakis\, Charalampos Platan
 os\, Thanos\nTolias.
DTSTAMP:20261023T060850Z
END:VEVENT
BEGIN:VEVENT
UID:6adaf9f2d3eb4
DTSTART;TZID=America/Toronto:20261009T153000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20261009T163000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/tutte-colloq
 uium-jake-doliskani-quantum-money-wiesner
SUMMARY:Tutte Colloquium | Jake Doliskani\, Quantum Money: From Wiesner to\
 nStandard Assumptions
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Jake Doliskani\n\nAFFILIATION:\n McMaster University
  \n\nLOCATION:\n MC 5501\n\nABSTRACT: Quantum money is one of the earlies
 t ideas in quantum\ncryptography: a banknote is represented by a quantum s
 tate that cannot\nsimply be copied. Wiesner’s original proposal required
  the bank to\nverify every transaction\, motivating the notion of public-k
 ey quantum\nmoney\, where anyone can verify a banknote while only the bank
  can\ncreate new ones.\n\nIn this talk\, I will trace the story of quantum
  money from Wiesner’s\nscheme\, through the hidden-subspace construction
  of Aaronson and\nChristiano\, to Zhandry’s recent construction from abe
 lian group\nactions. I will discuss why previous proposals were either bro
 ken or\nrelied on non-standard assumptions\, and then present recent work\
 nshowing that Zhandry’s construction can be based\, in the generic\ngrou
 p-action model\, on the standard group-action discrete logarithm\nassumpti
 on. I will conclude with the main idea behind the security\nproof.
DTSTAMP:20261023T060850Z
END:VEVENT
BEGIN:VEVENT
UID:6adaf9f2d452c
DTSTART;TZID=America/Toronto:20261007T100000
SEQUENCE:0
TRANSP:TRANSPARENT
DTEND;TZID=America/Toronto:20261007T110000
URL:https://uwaterloo.ca/combinatorics-and-optimization/events/crypto-readi
 ng-group-quantum-computing-mojtaba-fadavi-and
SUMMARY:Crypto Reading Group on quantum computing | Mojtaba Fadavi and Taha
 \nHedayat\, Quantum Circuits
CLASS:PUBLIC
DESCRIPTION:SPEAKER:\n Mojtaba Fadavi & Taha Hedayat\n\nAFFILIATION:\n Univ
 ersity of Waterloo\n\nROOM:\n MC 5501\n\nABSTRACT: Equipped with the know
 ledge of quantum information\, we\npresent how to use quantum states to bu
 ild a quantum algorithm. While\nclassical circuits represent how one makes
  algorithms using the bits 0\nand 1\, quantum circuits represent how one m
 akes algorithms using\nqubits $\\ket{\\alpha} = \\alpha_0 \\ket{0} + \\alp
 ha_1\\ket{1}$. In this\npresentation\, we will introduce the definition an
 d presentation of\nquantum gates. Starting with 1-qubit gates and expandin
 g to n-qubit\ngates. We also present the standard gates such as the Pauli 
 Gates\,\nCNOT\, CCNOT\, SWAP\, etc. Then we proceed to see the effects and
 \ninteractions of these gates along with some measurements.
DTSTAMP:20261023T060850Z
END:VEVENT
END:VCALENDAR