William Umboh
@swumboh.bsky.social
Lecturer in Computational Theory, School of Computing and Information Systems, University of Melbourne. Interests: Theoretical computer science and combinatorial optimisation, focussing on approximation and online algorithms. williamumboh.com
Pinned
William Umboh
@swumboh.bsky.social
· Apr 3
Not exactly rock star, but at least log star
Usually, diagonalization is used to prove that the problem of deciding whether a given Turing machine M accepts a given input string w is undecidable.
Some places, (eg Stanford CS103), make an analogy to the liar paradox.
The following seems to more directly reflect the liar paradox. Am I right?
Some places, (eg Stanford CS103), make an analogy to the liar paradox.
The following seems to more directly reflect the liar paradox. Am I right?
November 8, 2025 at 7:28 AM
Usually, diagonalization is used to prove that the problem of deciding whether a given Turing machine M accepts a given input string w is undecidable.
Some places, (eg Stanford CS103), make an analogy to the liar paradox.
The following seems to more directly reflect the liar paradox. Am I right?
Some places, (eg Stanford CS103), make an analogy to the liar paradox.
The following seems to more directly reflect the liar paradox. Am I right?
❌ paying for search engine optimization
✅ using a search term as the shop name
✅ using a search term as the shop name
October 25, 2025 at 12:36 AM
❌ paying for search engine optimization
✅ using a search term as the shop name
✅ using a search term as the shop name
Reposted by William Umboh
For nearly 80 years, an algorithm called the simplex method has been one of the most widely used tools for when a logistical decision needs to be made under complex constraints. A new update makes it faster than ever. www.quantamagazine.org/researchers-...
Researchers Discover the Optimal Way To Optimize | Quanta Magazine
The leading approach to the simplex method, a widely used technique for balancing complex logistical constraints, can’t get any better.
www.quantamagazine.org
October 13, 2025 at 2:30 PM
For nearly 80 years, an algorithm called the simplex method has been one of the most widely used tools for when a logistical decision needs to be made under complex constraints. A new update makes it faster than ever. www.quantamagazine.org/researchers-...
Reposted by William Umboh
SODA notifications are in the inboxes, and this paper will be in the conference :)
This is my second paper using extended formulations to prove running time lower bounds. I am surprised that people have been sleeping on this angle, but happy to fill in the gap where needed
This is my second paper using extended formulations to prove running time lower bounds. I am surprised that people have been sleeping on this angle, but happy to fill in the gap where needed
An unconditional lower bound for the active-set method in convex quadratic maximization
We prove that the active-set method needs an exponential number of iterations in the worst-case to maximize a convex quadratic function subject to linear constraints, regardless of the pivot rule used...
arxiv.org
October 3, 2025 at 2:14 PM
SODA notifications are in the inboxes, and this paper will be in the conference :)
This is my second paper using extended formulations to prove running time lower bounds. I am surprised that people have been sleeping on this angle, but happy to fill in the gap where needed
This is my second paper using extended formulations to prove running time lower bounds. I am surprised that people have been sleeping on this angle, but happy to fill in the gap where needed
Just realized I had bought “Indistractable” by Nir Eyal more than a month ago, and was too distracted to read it
October 14, 2025 at 8:39 PM
Just realized I had bought “Indistractable” by Nir Eyal more than a month ago, and was too distracted to read it
Generating memes for a models of computation class
October 7, 2025 at 8:42 AM
Generating memes for a models of computation class
Reposted by William Umboh
The Swiss Winter School in TCS 2026 will take place January 25-30, featuring amazing speakers Ankur Moitra (MIT), Avishay Tal (UC Berkeley), and Vera Traub (ETHZ).
Application deadline: October 24
More information: theory.epfl.ch/WinterSchool...
Application deadline: October 24
More information: theory.epfl.ch/WinterSchool...
Swiss Winter School on Theoretical Computer Science
theory.epfl.ch
September 29, 2025 at 1:31 PM
The Swiss Winter School in TCS 2026 will take place January 25-30, featuring amazing speakers Ankur Moitra (MIT), Avishay Tal (UC Berkeley), and Vera Traub (ETHZ).
Application deadline: October 24
More information: theory.epfl.ch/WinterSchool...
Application deadline: October 24
More information: theory.epfl.ch/WinterSchool...
Reposted by William Umboh
It feels like an insult to the notion of objective reality to invoke “experts” to weigh in on a numerical fact you can verify with a pocket calculator
September 26, 2025 at 3:42 AM
It feels like an insult to the notion of objective reality to invoke “experts” to weigh in on a numerical fact you can verify with a pocket calculator
Reposted by William Umboh
Official petition to the 🇦🇺 govt: make part-time PhD students' stipends tax-exempt!
www.aph.gov.au/e-petitions/...
Stipends are low but at least tax-exempt. Unless they go part time, then it becomes taxable. This disproportionately affects PhD students w/ care duties, health issues, young children..
www.aph.gov.au/e-petitions/...
Stipends are low but at least tax-exempt. Unless they go part time, then it becomes taxable. This disproportionately affects PhD students w/ care duties, health issues, young children..
e-petitions
e-petitions
www.aph.gov.au
September 25, 2025 at 10:38 AM
Official petition to the 🇦🇺 govt: make part-time PhD students' stipends tax-exempt!
www.aph.gov.au/e-petitions/...
Stipends are low but at least tax-exempt. Unless they go part time, then it becomes taxable. This disproportionately affects PhD students w/ care duties, health issues, young children..
www.aph.gov.au/e-petitions/...
Stipends are low but at least tax-exempt. Unless they go part time, then it becomes taxable. This disproportionately affects PhD students w/ care duties, health issues, young children..
Hi, I’d like to report a wormhole: Departing Hong Kong 0 mins ago and arriving in Melbourne in 0 minutes.
September 13, 2025 at 8:30 PM
Hi, I’d like to report a wormhole: Departing Hong Kong 0 mins ago and arriving in Melbourne in 0 minutes.
Konnichiwa! My name is Weliam
September 11, 2025 at 8:28 AM
Konnichiwa! My name is Weliam
Reposted by William Umboh
Delighted to announce I have joined the board of the Association for Computational Learning (ACL) as Diversity and Inclusion Officer!
With your help, let's strive to make the learning theory conferences and community more inclusive and welcoming to all!
ACL website: learningtheory.org
With your help, let's strive to make the learning theory conferences and community more inclusive and welcoming to all!
ACL website: learningtheory.org
Association for Computational Learning (ACL)
learningtheory.org
September 2, 2025 at 11:01 PM
Delighted to announce I have joined the board of the Association for Computational Learning (ACL) as Diversity and Inclusion Officer!
With your help, let's strive to make the learning theory conferences and community more inclusive and welcoming to all!
ACL website: learningtheory.org
With your help, let's strive to make the learning theory conferences and community more inclusive and welcoming to all!
ACL website: learningtheory.org
Reposted by William Umboh
Please nominate researchers for the #FOCS2025 Test of Time awards! This "recognizes papers published in past FOCS for their substantial, lasting, broad, and currently relevant impact."
Nominations due by ⏰ Sep 15. Details and guidelines: tc.computer.org/tcmf/2025/08...
Nominations due by ⏰ Sep 15. Details and guidelines: tc.computer.org/tcmf/2025/08...
FOCS Test of Time Award - Call for Nominations 2025 - IEEE Computer Society Technical Committee on Mathematical Foundations of Computing
FOCS 2025 Test of Time Awards Call for Nominations The 2025 FOCS Test of Time Awards, awarded annually, recognize papers published in the Proceedings of the Annual IEEE Symposium on Foundations of...
tc.computer.org
August 26, 2025 at 9:35 PM
Please nominate researchers for the #FOCS2025 Test of Time awards! This "recognizes papers published in past FOCS for their substantial, lasting, broad, and currently relevant impact."
Nominations due by ⏰ Sep 15. Details and guidelines: tc.computer.org/tcmf/2025/08...
Nominations due by ⏰ Sep 15. Details and guidelines: tc.computer.org/tcmf/2025/08...
Wow, this is brilliant work by @samwho.dev! It even has a built in fidget toy (of course I kept clicking on the dog for the ❤️s).
August 26, 2025 at 12:55 PM
Wow, this is brilliant work by @samwho.dev! It even has a built in fidget toy (of course I kept clicking on the dog for the ❤️s).
As a highly visual learner, I’m lovijg this visual introduction to big O!
✨ Big O ✨
Let me take you on a visual introduction to what big O notation is in my new blog post: samwho.dev/big-o.
With big O notation you can better understand how algorithms will perform in practice, finding orders of magnitude improvements often with very simple changes to your code.
Let me take you on a visual introduction to what big O notation is in my new blog post: samwho.dev/big-o.
With big O notation you can better understand how algorithms will perform in practice, finding orders of magnitude improvements often with very simple changes to your code.
August 26, 2025 at 12:44 PM
As a highly visual learner, I’m lovijg this visual introduction to big O!
Really happy with how the algorithms display went at the University of Melbourne Open Day! We gave a demo of en.m.wikipedia.org/wiki/Boyer%E... using playing cards as votes and suits as the parties. Pairing up cards of different suits made it really clear what the algorithm is doing, IMO.
August 17, 2025 at 7:51 AM
Really happy with how the algorithms display went at the University of Melbourne Open Day! We gave a demo of en.m.wikipedia.org/wiki/Boyer%E... using playing cards as votes and suits as the parties. Pairing up cards of different suits made it really clear what the algorithm is doing, IMO.
Guess what I found on a random walk in Melbourne
August 15, 2025 at 8:49 AM
Guess what I found on a random walk in Melbourne
Reposted by William Umboh
If you’re at a party that has six people, Ramsey theory says there must be three people who know each other, or three people who are all strangers. But if there are only five people, this statement is not true.
Why the Key to a Mathematical Life is Collaboration | Quanta Magazine
Fan Chung, who has an Erdős number of 1, discusses the importance of connection — both human and mathematical.
www.quantamagazine.org
July 29, 2025 at 8:04 PM
If you’re at a party that has six people, Ramsey theory says there must be three people who know each other, or three people who are all strangers. But if there are only five people, this statement is not true.
Reposted by William Umboh
i think both sides are to blame here
July 29, 2025 at 12:50 PM
i think both sides are to blame here
Reposted by William Umboh
The student and postdoc travel grant applications are open!
focs.computer.org/2025/travel-...
focs.computer.org/2025/travel-...
a little girl is riding a blue toy car with the words go go go written on it .
Alt: a little girl is riding a blue toy car with the words go go go written on it .
media.tenor.com
July 28, 2025 at 9:05 AM
The student and postdoc travel grant applications are open!
focs.computer.org/2025/travel-...
focs.computer.org/2025/travel-...
Sign in ice cream store Fluffy Torpedo in Brunswick: Fear not which choice you make, free will is an illusion
July 26, 2025 at 6:19 AM
Sign in ice cream store Fluffy Torpedo in Brunswick: Fear not which choice you make, free will is an illusion
Reposted by William Umboh
Just one more week left to apply for the International Visitor Program at SMRI! Please share this incredible opportunity with your #MathSky networks
Full T+Cs and application: mathematical-research-institute.sydney.edu.au/internationa...
Full T+Cs and application: mathematical-research-institute.sydney.edu.au/internationa...
July 25, 2025 at 5:11 AM
Just one more week left to apply for the International Visitor Program at SMRI! Please share this incredible opportunity with your #MathSky networks
Full T+Cs and application: mathematical-research-institute.sydney.edu.au/internationa...
Full T+Cs and application: mathematical-research-institute.sydney.edu.au/internationa...