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gloftus commented on A new bridge links the math of infinity to computer science   quantamagazine.org/a-new-... · Posted by u/digital55
veltas · 2 months ago
Sorry I apologise, I didn't realise I wasn't allowed to care about countability.
gloftus · 2 months ago
Countability is the whole point, there's no need to apologize. I was merely offering the perspective that "towers of infinity" is possibly the least useful consequence that comes from defining the notion of countability. To my mind, what we really reap from Cantor's work is a better understanding of the topology of the real numbers. But you have to define countability first in order to understand what uncountability really implies.
gloftus commented on A triangle whose interior angles sum to zero   johndcook.com/blog/2025/1... · Posted by u/tzury
gloftus · 2 months ago
Worth noting that the hyperbolic triangle in the article contains "points at infinity" which are not actually a part of the hyperbolic plane, so this is really an "improper triangle" as the article notes. One could construct a similar improper triangle in the Euclidean plane that consisted of two parallel lines meeting at infinity. Such a triangle would still have 180 degrees of internal angle but it's area and perimeter would be infinite.
gloftus commented on A new bridge links the math of infinity to computer science   quantamagazine.org/a-new-... · Posted by u/digital55
veltas · 3 months ago
The difference between infinities is I can write every possible fraction on a piece of A4 paper, if the font gets smaller and smaller. I can say where to zoom in for any fraction.

I can't do that for real numbers.

gloftus · 3 months ago
You can't enumerate the real numbers, but you can grab them all in one go - just draw a line!

The more I learn about this stuff, the more I come to understand how the quantitative difference between cardinalities is a red herring (e.g. CH independent from ZFC). It's the qualitative difference between these two sets that matter. The real numbers are richer, denser, smoother, etc. than the natural numbers, and those are the qualities we care about.

gloftus commented on A new bridge links the math of infinity to computer science   quantamagazine.org/a-new-... · Posted by u/digital55
zkmon · 3 months ago
.. because that is where you are allowed to challenge some biblical stories of the math without the fear of expulsion from the elite clubs.

Most of math history is stellar, studded with great works of geniuses, but some results were sanctified and prohibited for questioning due to various forces that were active during the times.

Application of regular logic such as comparison, mapping, listing, diagonals, uniqueness - all are the rules that were bred in the realms of finiteness and physical world. You can't use these things to prove some theories about things are not finite.

gloftus · 3 months ago
This isn't iconoclasm, it's ignorance.
gloftus commented on The hunt for the missing data type   hillelwayne.com/post/grap... · Posted by u/todsacerdoti
ylow · 2 years ago
I think this is because a graph is not a data-structure nor a data-type. It is really an abstraction.

Fundamentally, all I need to define a graph is a set of vertices v \in V and function Neighbors(v). And that really is all is needed for the most foundational set of graph algorithms.

Everything else are case-by-case constraints. Does A->B imply B->A? is the node set partitionable with certain constraints? Are there colors? labels?

To make things even more general I can go up one level and consider the hypergraph. In which case I just have a set of vertices, and a set of sets of vertices. This can be represented in a myriad of different ways depending on what you are interested in. Of which (non-hyper) graph is simply a special case.

An alternative way to think about it perhaps from the database perspective, is that its a query optimization and indexing problem. Depending on what questions you want to ask about the graph, there will be different ways to represent the graph to answer the question better. Just like there is not one way to represent the abstraction called "Table", there is not one way to do "Graph" either. It really depends on the questions you care about.

gloftus · 2 years ago
Yes, graphs are ubiquitous because they are so abstract. They live on the same level of abstraction as pure numbers. There are useful "numerical" libraries that exist, and by analogy I think you could say there are also useful "graphical" libraries that exist. But we don't really have "number" libraries, and we don't really have "graph" libraries, because those concepts are a bit too abstract to write APIs against.
gloftus commented on Particle Physicists Continue to Make Empty Promises   backreaction.blogspot.com... · Posted by u/chmaynard
prof-dr-ir · 5 years ago
79 points as of now. And how many points would hacker news have given to the Nature comment by Giudice and Gianotti?

It is both curious and sad to see the outsize attention given to bitter polemicists (and not just in physics).

Please read https://www.nature.com/articles/s41567-020-01054-6 .

Edit: downvotes? let me rephrase: if you care about particle physics then there was no reason to ignore the original proposal. if you care about outrage, on the other hand...

gloftus · 5 years ago
I think you are being down voted because you appear to have an ax to grind rather than a useful perspective on the issue.
gloftus commented on A ‘viral’ new bird song in Canada is causing sparrows to change their tune   gizmodo.com/a-viral-new-b... · Posted by u/Osiris30
marklacey · 6 years ago
I spent two summers in an apartment in San Francisco that was near the nest of what I assume was a nightingale.

Every night around midnight it would start singing. It would loop through maybe 8 songs. Some of them sounded very much like the local environment. For example one song was pretty much identical to sirens that I would periodically hear.

It would last for an hour or two each night. I don’t know where the bird went the rest of the year. That was almost ten years ago and I still miss falling asleep to that.

gloftus · 6 years ago
We have those in Boston, I always thought they were mockingbirds.

https://www.youtube.com/watch?v=YhiyxmWI95Q

u/gloftus

KarmaCake day77December 30, 2013View Original