Live data from Hacker News

Ask HN: What's the hardest problem you've ever solved?

news.ycombinator.com

131–140 of 441 posts

Re: Ask HN: What's the hardest problem you've ever solved?

#131
Always-On Computer Vision [1]:

Summary: Qualcomm wanted me to devise a computer vision solution that was nearly three orders of magnitude power-efficient than what they had then. There was a clear justification existing as to why such a drastic improvement was needed. Nobody had a solution in spite of trying for a long time. Most laughed it as impossible. I started by looking for a proof as to why it could not be done if it indeed could not be done. After some three months of pulling my hair, I started getting glimpses of how to do it. Some three months later, I could convince myself and a few others that it is doable. Some three months later, the local team was fully convinced. Some three months later, the upper management was convinced that the research phase was over.

Details:

I was told to reduce power consumption for an existing computer vision solution by nearly three orders of magnitude. This included end-to-end power consumption including camera as well as power for computer vision computations.

No one in the industry knew how to do this. Many industry experts laughed at the goal itself.

To make it worse, I by myself had no prior expertize in computer vision, nor in camera design, though I knew image processing. I was assigned to the project solely because of my brand name with the company. Being ignorant perhaps helped since else I may not even have accepted the assignment.

I was told this is to be a five-years type research program, given the agressive goal.

I was told that the company was ready to do change whatever is needed to make this happen, be it the camera design (including pixel circuit), processor architecture, computer vision algorithms, even optics and packaging.

With no starting point in hand (and in fact a false start assumed based on half-baked ideas from one university), I had head-aches daily for more than a month. Most of this was to learn and deep dive into the prior art.

The goal I assumed was to either solve the problem, or show a theoretical basis for why it cannot be solved. (In hindsight, to solve a challenging problem, try to prove why it cannot be solved, since even that is usually hard, and you may prove yourself wrong in the process by solving it!)

There was no assigned team, given that there was no solution in mind. There were people with varied skillsets (optics, packaging, digital circuits) to help as per need.

Three months in, I had some ideas for how it could work. Six months in, there were three more engineers on the project working under me on a near full-time basis. And some were complaining that we don't know what we were doing. Seven months in, I had Excel-level calculations to show that it can work, and actually a simpler solution than what I had in mind at the three-month point. Nine months in, with about seven people working, the team was convinced of the solution, as validated via rough circuit design and simulations. By the end of the year, senior management was convinced that we have solved the problem and the research phase is over. We had an estimated five years to solve the problem, and the solution achieved three times less power than the target!

The solution was a mix of several new inventions (one was given gold rating by the company) and significant power savings obtained just by careful design. Unfortunately, I cannot talk much about the solution itself.

We started showing early preview of the capabilities (under NDA and without disclosing how we solved it) at multiple Tier 1 companies, and saw their jaws drop. At one company, one whispered to their team members, "Are these guys kidding?!". At another company, someone smiled silently for half-an-hour till we started showing the system emulator.

Soon, MIT Technology Review talked about the work [1].

I have since then left the company, so do not know much about the current state of the project, other than additional news coverage received over the time. Additional references are there in my LinkedIn profile.

PS: I have solved many hard problems through my career, have written about the one that gave me the most head-aches. Here is a list of some other ones [2].

[1] https://www.technologyreview.com/s/603964/qualcomm-wants-you...

[2] https://news.ycombinator.com/item?id=14222590

Re: Ask HN: What's the hardest problem you've ever solved?

#132
post #90

I somehow decided I needed to cheat to pass a certain exam because I was basically crap at memorizing stuff. So I used an analogue wireless headphone, an induction loop around my neck and a mobile phone. Since I lacked an accomplice to dictate, I read aloud the hundreds of pages and recorded myself, careful to preserve and properly serialize things like complex formulas. This was before the era of iPods and SDCard pl…

That's creative AF.

IMO if you can get around a system that's as good as going through it. It usually takes a certain kind of ingenuity to be able to do, so I can't be mad at it.

Re: Ask HN: What's the hardest problem you've ever solved?

#133
A simplified universal parsing format (AST) that equally describes all languages. It needs to allow seamless switching between different languages in the same file and also allow recursively nesting of different languages within each other without resulting in a deviating from the simplified parse format.

The solution is written and it appears correct and viable. As in all things related to parsers the devil's in the details in attempts to prove edge cases with exotic tests and use cases.

Re: Ask HN: What's the hardest problem you've ever solved?

#135
How to be happy.

For me it turned out to be jettisoning all of the stuff from my life that didn’t feel meaningful and reorienting my life such that all of my major time commitments positively impact things that I consider to be personal values.

This includes: hobbies, non-profits, and my job.

This does not mean I live an ascetic life. Instead, I live one that I personally find meaningful.

Re: Ask HN: What's the hardest problem you've ever solved?

#138

I recovered the redacted text in this image: https://btcblockchain.files.wordpress.com/2015/02/e2.png

How did you approach this problem and solve it?

My approach would be to brute-force match the pixels word by word.

Re: Ask HN: What's the hardest problem you've ever solved?

#139

Fixing a SRAM 11 speed GX rear shifter on my mountain bike. I was on a downhill MTB holiday and fell off, snapping the thumb trigger on my rear gear shifter. Replacing the shifter is usually like a £30 part, but I was in an alpine resort in summer so the shops that stocked them were charging nearly £100! I had my tools and some super glue so sat down to repair it. The snapped part fixed in two minutes but getting tha…

Are you making YouTube videos of your mountain biking adventures or just videos for fun? I would be keen to see them as I am getting into it now myself.

Re: Ask HN: What's the hardest problem you've ever solved?

#140
post #131

Always-On Computer Vision [1]: Summary: Qualcomm wanted me to devise a computer vision solution that was nearly three orders of magnitude power-efficient than what they had then. There was a clear justification existing as to why such a drastic improvement was needed. Nobody had a solution in spite of trying for a long time. Most laughed it as impossible. I started by looking for a proof as to why it could not be don…

> (In hindsight, to solve a challenging problem, try to prove why it cannot be solved, since even that is usually hard, and you may prove yourself wrong in the process by solving it!)

This is how I approach almost any hard problem if I get stuck at some point. Attempt to prove that the next step is impossible - a missing link in the attempted proof usually reveals some deeper structure or invariant that you can use for solving the problem.

It's a great way to force yourself into a different perspective and distill the problem down further.

Post reply on HN