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ramity commented on Ask HN: Are there examples of 3D printing data onto physical surfaces?    · Posted by u/catapart
ramity · a month ago
I run a business that makes 3d printed braille molds that are used to repeatably emboss paper. I haven't considered the molds being offline storage, but I suppose they are. I mostly operate with the assumption of a shelf life of 10 years for the PETG molds, but ink free, embossed paper has excellent lifespan if stored correctly.

I guess you could consider it an "offline datastore as a service." It would be a pretty good offline storage of keys with a way to request a paper copy. Certainly issues of trust and physical security but wrapping it with encryption would be easy. Also benefit from your government's legal protections for mail. There might actually be a usecase here.

Couple fast facts:

- Current 26 * 32 = 832 cells * 6 dot braille = 4992 bits/mold/page

- Possible 28 * 34 = 952 cells * 6 dot braille = 5712 bits/mold/page

- Maybe some more headroom, but that's what is possible with current spacings

ramity commented on How to wrangle non-deterministic AI outputs into conventional software? (2025)   domainlanguage.com/articl... · Posted by u/druther
ramity · 2 months ago
Let me first start off by saying I and many others have stepped in this pitfall. This is not an attack, but a good faith attempt to share painfully acquired knowledge. I'm actively using AI tooling, and this comment isn't a slight on the tooling but rather how we're all seemingly putting the circle in the square hole and it fits.

Querying an LLM to output its confidence in its output is a misguided pattern despite being commonly applied by many. LLMs are not good at classification tasks as the author states. They can "do" it, yes. Perhaps better than random sampling can, but random sampling can "do" it as well. Don't get too tied to that example. The idea here is that if you are okay with something getting the answer wrong every so often, LLMs might be your solve, but this is a post about conforming non-deterministic AI into classical systems. Are you okay if your agentic agent picks the red tool instead of the blue tool 1%, 10%, etc of the time? If so, you're never not going to be wrangling, and that's the reality often left unspoken when integrating these tools.

While tangential to this article, I believe its worth stating that when interacting with an LLM in any capacity, remember your own cognitive biases. You often want the response to work, and while generated responses may look good and fit your mental model, it requires increasingly obscene levels of critical evaluation to see through the fluff.

For some, there will be inevitable dissonance reading this, but consider that these experiments are local examples. Its lack of robustness will become apparent with large scale testing. The data spaces these models have been trained on are unfathomably large in both quantity and depth, but under/over sampling bias will be ever present (just to name one).

Consider the the following thought experiment: You are an applicant for a job submitting your resume with knowledge it will be fed into an LLM. Let's confine your goal into something very simple. Make it say something. Let's oversimplify for the sake of the example and say complete words are tokens. Consider "collocations". [Bated] breath, [batten] down, [diametrically] opposed, [inclement] weather, [hermetically] sealed. Extend this to contexts. [Oligarchy] government, [Chromosome] biology, [Paradigm] technology, [Decimate] to kill. With this in mind, consider how each word of your resume "steers" the model's subsequent response, and consider how the data each model is trained on can subtly influence its response.

Now let's bring it home and tie the thought experiment into confidence scoring in responses. Let's say its reasonable to assume that the results of low accuracy/low confidence models are less commonly found on the internet than higher performing ones. If that can be entertained, extend the argument to confidence responses. Maybe the term "JSON" or any other term used in the model input is associated with high confidences.

Alright, wrapping it up. The end point here is that the model output provided confidence value is not the likelihood of the answer provided in the response but rather the most likely value following the stream of tokens in the combined input and output. The real sampled confidence values exist closer to code, but they are limited to each token. Not series of tokens.

ramity commented on VPN location claims don't match real traffic exits   ipinfo.io/blog/vpn-locati... · Posted by u/mmaia
seszett · 3 months ago
They don't have to assume that traffic is efficiently routed, on the contrary if they can have a <1ms RTT from London to a server, the speed of light guarantees that that server is not in Mauritius EVEN if the traffic was efficiently routed.

It just can't be outside England, just one 0.4ms RTT as seen here is enough to be certain that the server is less then 120 km away from London (or wherever their probe was, they don't actually say, just the UK).

RTT from a known vantage point gives an absolute maximum distance, and if that maximum distance is too short then that absolutely is enough to ascertain that a server is not in the country it claims to be.

ramity · 3 months ago
I see I was mistaken, but I'm tempted to continue poking holes. Trying a different angle, though it may be a stretch, but could a caching layer within the VPN provider cause these sort of "too fast" RTTs?

Let's say you're a global VPN provider and you want to reduce as much traffic as possible. A user accesses the entry point of your service to access a website that's blocked in their country. For the benefit of this thought experiment, let's say the content is static/easily cacheable or because the user is testing multiple times, that dynamic content becomes cached. Could this play into the results presented in this article? Again, I know I'm moving goalposts here, but I'm just trying to be critical of how the author arrived at their conclusion.

ramity commented on VPN location claims don't match real traffic exits   ipinfo.io/blog/vpn-locati... · Posted by u/mmaia
Pyrolol · 3 months ago
The speed of light provides a limit on distance for a given RTT, and taking the examples in the article which are less than 0.5ms and considering the speed of light (300km/ms) the measured exit countries must be accurate.

The speed of light in fiber which probably covers most of the distance is also even slower due to refraction (about 2/3).

ramity · 3 months ago
Thanks for your informative reply. I see now I was approaching this incorrectly. I was considering drawing conclusions from a high RTT rather than a RTT so small it would be impossible to have gone the distance.
ramity commented on VPN location claims don't match real traffic exits   ipinfo.io/blog/vpn-locati... · Posted by u/mmaia
ramity · 3 months ago
Contrasting take: RTT and a service providing black box knowledge is not equivalent to knowledge of the backbone. To assume traffic is always efficiently routed seems dubious when considering a global scale. The supporting infrastructure of telecom is likely shaped by volume/size of traffic and not shortest paths. I'll confess my evaluation here might be overlooking some details. I'm curious on others' thoughts on this.
ramity commented on iPhone Typos? It's Not Just You – The iOS Keyboard Is Broken [video]   youtube.com/watch?v=hksVv... · Posted by u/walterbell
ramity · 3 months ago
35m ago edit: Apple uses many predictive systems for typing. My sentiment in pointing out just slide to type might be misguided as it does not exist in a vacuum. I'd love to see these tests redone with slide to type disabled. I'm leaving the original comment below for reference.

Slide to type. This "issue" is at most 6 years old for iOS users.

Turn off slide to type if you do not use it. Slide to type does key resizing logic. This is the direct cause of this issue. Please upvote this comment for visibility.

Please reply if you think I'm wrong. I see this get posted frequently enough I'm actually losing it.

Please refer to https://youtu.be/hksVvXONrIo?si=XD7AKa8gTl85_rJ6&t=72 (timestamp 1:12) to see that slide to type is enabled.

ramity commented on WiFi-3D-Fusion – Real-time 3D motion sensing with Wi-Fi   github.com/MaliosDark/wif... · Posted by u/aerosol
michelsedgh · 7 months ago
what i want to know is if you need multiple senders and receivers, or you just run it on a esp32 and it can visualize? usually they need a sender and a receiver to make sense of it all?
ramity · 7 months ago
I didn't see any reference to a sender or actively blasting RF from the same access point. I think the approach relies on other signal sources creating reflections to a passively monitoring access point and attempting to make sense of that.
ramity commented on WiFi-3D-Fusion – Real-time 3D motion sensing with Wi-Fi   github.com/MaliosDark/wif... · Posted by u/aerosol
eig · 7 months ago
Seems like it is based on this paper from CVPR 2024:

https://aiotgroup.github.io/Person-in-WiFi-3D/

Frankly I'm shocked it's possible to do this with that level of resolution.

ramity · 7 months ago
5GHz WiFi has a wavelength of ~6cm and 2.4GHz ~12.5cm. Anything achieving smaller is a result of interferometry or a non WiFi signal. Mentioning this might not add much substance to the conversation, but it felt worth adding.
ramity commented on WiFi-3D-Fusion – Real-time 3D motion sensing with Wi-Fi   github.com/MaliosDark/wif... · Posted by u/aerosol
ramity · 7 months ago
I'm interested but am also incredibly dubious. Not because it seems impossible but the opposite. On one hand, an open source repo like this making an approach for hackable extension should be praised, but the "Why Built WiFi-3D-Fusion" section[0] gives me very, very bad vibes. Here's some excerpts I especially take issue with:

> "Why? Because there are places where cameras fail, dark rooms, burning buildings, collapsed tunnels, deep underground. And in those places, a system like this could mean the difference between life and death."

> "I refuse to accept 'impossible.'"

WiFi sensing is an established research domain that has long struggled with line of sight requirements, signal reflection, interference, etc. This repo has the guise of research, but it seems to omit the work of the field it resides in. It's one thing to detect motion or approximately track a connected device through space, but "burning buildings, collapsed tunnels, deep underground" are exactly the kind of non-standardized environments where WiFi sensing performs especially poorly.

I hate to judge so quickly based on a readme, but I'm not personally interested in digging deeper or spinning up an environment. Consider this before aligning with my sentiment.

[0] https://github.com/MaliosDark/wifi-3d-fusion/blob/main/READM...

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https://github.com/ramity "It's closed source until it isn't."

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