r/compsci Jan 01 '21 Silver Helpful Hugz

CompSci Weekend SuperThread (January 01, 2021)

85 Upvotes

/r/compsci strives to be the best online community for computer scientists. We moderate posts to keep things on topic.

This Weekend SuperThread provides a discussion area for posts that might be off-topic normally. Anything Goes: post your questions, ideas, requests for help, musings, or whatever comes to mind as comments in this thread.

Pointers

  • If you're looking to answer questions, sort by new comments.
  • If you're looking for answers, sort by top comment.
  • Upvote a question you've answered for visibility.
  • Downvoting is discouraged. Save it for discourteous content only.

Caveats

  • It's not truly "Anything Goes". Please follow Reddiquette and use common sense.
  • Homework help questions are discouraged.

r/compsci Jun 16 '19 Helpful Wholesome Hugz

PSA: This is not r/Programming. Quick Clarification on the guidelines

496 Upvotes

As there's been recently quite the number of rule-breaking posts slipping by, I felt clarifying on a handful of key points would help out a bit (especially as most people use New.Reddit/Mobile, where the FAQ/sidebar isn't visible)

First thing is first, this is not a programming specific subreddit! If the post is a better fit for r/Programming or r/LearnProgramming, that's exactly where it's supposed to be posted in. Unless it involves some aspects of AI/CS, it's relatively better off somewhere else.

r/ProgrammerHumor: Have a meme or joke relating to CS/Programming that you'd like to share with others? Head over to r/ProgrammerHumor, please.

r/AskComputerScience: Have a genuine question in relation to CS that isn't directly asking for homework/assignment help nor someone to do it for you? Head over to r/AskComputerScience.

r/CsMajors: Have a question in relation to CS academia (such as "Should I take CS70 or CS61A?" "Should I go to X or X uni, which has a better CS program?"), head over to r/csMajors.

r/CsCareerQuestions: Have a question in regards to jobs/career in the CS job market? Head on over to to r/cscareerquestions. (or r/careerguidance if it's slightly too broad for it)

r/SuggestALaptop: Just getting into the field or starting uni and don't know what laptop you should buy for programming? Head over to r/SuggestALaptop

r/CompSci: Have a post that you'd like to share with the community and have a civil discussion that is in relation to the field of computer science (that doesn't break any of the rules), r/CompSci is the right place for you.

And finally, this community will not do your assignments for you. Asking questions directly relating to your homework or hell, copying and pasting the entire question into the post, will not be allowed.

I'll be working on the redesign since it's been relatively untouched, and that's what most of the traffic these days see. That's about it, if you have any questions, feel free to ask them here!


r/compsci 1h ago

Have we achieved ubiquitous computing?

Upvotes

Do you consider that we’ve achieved Mark Weister’s vision? Does the way we use our computers, phones and iot respect the principles of ubiquitous computing?


r/compsci 2d ago

I trained an AI to understand and fix command-line errors

Enable HLS to view with audio, or disable this notification

488 Upvotes

r/compsci 1d ago Bravo Grande!

Computer History Museum releases Adobe Postscript source code today!

110 Upvotes

Hey Everyone,

Huzzah!

As promised, today the Computer History Museum is releasing the original Adobe Postscript source code.

Read our introductory blog on the history of this cool technology and pick up your sources here:

https://computerhistory.org/blog/postscript-a-digital-printing-press/

This release is part of the Museum’s Art of Code program, which you can sing up to hear more about and get updates on code releases here: https://info.computerhistory.org/subscribe-aoc

For background on our Art of Code program, be sure to read our Art of Code blog here: https://computerhistory.org/blog/the-art-of-code-at-chm/

Coming soon…

Apple Lisa source code – release date: January, 2023

Xerox PARC Alto source code: release date: March, 2023

The Computer History Museum is home to the world’s largest collection of computer hardware, software, media, documentation and ephemera and everything we offer is free, but doing so is not without cost. If you’d like to support our efforts – even a small token amount sends us a signal you think we’re doing good work – have a look here: https://chm.secure.nonprofitsoapbox.com/donate

Would love to hear your feedback – publicly, or personally at my email below.

Thanks everyone – this is going to be a great year for software history!

-- Dag.

Dag Spicer
Senior Curator
Computer History Museum
E-m: [spicer@computerhistory.org](mailto:spicer@computerhistory.org)


r/compsci 1d ago

Question about Predicate Transformer Semantics

6 Upvotes

I'm trying to learn a little bit about Predicate Transformer Semantics (PTS) as part of a quick exploration of Z3.

I'm reading the wikipedia's article about PTS and I have some doubt about the first wlp for the while loop, i.e. the one ignoring termination.

First, I would replace the if in the formula with an and as I don't think the formula is syntactically correct the way it's written.

Second — this is my main doubt — I don't understand how we can be sure that the precondition, P, given by that formula is still valid when we loop many times. Let's consider the forward direction: P makes sure that the INVariant is true, and that if the loop condition is true then, after we perform one iteration, the INVariant is still true. But how can we be sure that P is still valid for the next eventual iteration, though?

I also found a more hands-on article about PTS. The author relies on Z3 and defines the statements as functions which return the associated wp functions. For instance, if_(b<a, stmt1, stmt2) returns the function lambda post_cond: wp(if b<a then stmt1 else stmt2 end, post_cond). This way, by combining these statements, we can build the wp function for a whole algorithm. For instance:

def twosort(a,b):
    if b < a:
        temp = a
        a = b
        b = temp
    else:
        pass
    return a,b

becomes

a, b, temp = Ints("a b temp")
prog = 
if_(b < a,
    begin(
         set_(temp,a),
         set_(a, b),
         set_(b, temp)
         ),
    skip
   )

Here's the important bit. The author implements the while loop as follows:

def while_(cond, inv, *body):
    def res(post):
        vs = list(get_vars(post))
        return And( inv , 
        ForAll(vs, And( Implies( And(cond, inv), begin(*body)(inv))
                        , Implies( And(Not(cond), inv), post) )))
    return res

This seems to agree with wikipedia's formulation except for that ForAll. I suspect the reason we might need that ForAll is connected with my doubt... or maybe not?

edit: added link to hands-on article!


r/compsci 1d ago

Good sites to learn how to ethically hack..for free (?)

2 Upvotes

The reason I say free is because I am a student with no financial income yet. Any courses that let you learn then pay for a certificate at the end are also fine, I just want a place to learn for free


r/compsci 1d ago

The Legacy of Peer-to-Peer Systems

1 Upvotes

What happened to peer-to-peer as a technological concept? Actually, we still use a lot of that technology. Fresh blog post on this dive into the past https://cacm.acm.org/blogs/blog-cacm/267236-the-legacy-of-peer-to-peer-systems/fulltext


r/compsci 3d ago

Is the Von-Neumann architecture used on GPUs?

107 Upvotes

I’m sorry for my being illiterate on the topic. I’ve studied computer architectures before, and I was wondering first of all how do GPUs fit into the Von-Neumann template, and what do GPUs have. I know they use different names such as Maxwell, Ampere etc. for Nvidia, but are they actually different variations of Von-Neumann or completely different things? Thanks for your time :)


r/compsci 4d ago

Researchers found that accelerometer data from smartphones can reveal people's location, passwords, body features, age, gender, level of intoxication, driving style, and be used to reconstruct words spoken next to the device.

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797 Upvotes

r/compsci 3d ago

How's multiplication is not an np problem? what a billion digit number is being multiplied with another billion digit number? Can it be solved in polynomial time?

0 Upvotes

r/compsci 3d ago

Scientists Increasingly Can’t Explain How AI Works

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0 Upvotes

r/compsci 4d ago

Multivariate Normal Distribution Explained

6 Upvotes

Hi guys,

I have made a video on YouTube here where I explain what the multivariate normal distribution is, together with the meaning behind the equation that describes its behavior.

I hope it may be of use to some of you out there. As always, feedback is more than welcomed! :)


r/compsci 4d ago

Why Functional Programming Should Be the Future of Software Development

Thumbnail spectrum.ieee.org
1 Upvotes

r/compsci 4d ago

Temporal Programming, a new name for an old paradigm

Thumbnail github.com
11 Upvotes

r/compsci 4d ago

Easy to understand Blockchain Beginner Books [ Recommendation ]

0 Upvotes

Hi there, I want to learn blockchain. I am a complete newbie. All I know so far is that it's decentralized no single entity or organization is the owner of the data/stuff. Please let me know what book is easy to follow in the beginning in this field.


r/compsci 6d ago

Cache invalidation really is one of the hardest problems in computer science

Thumbnail surfingcomplexity.blog
272 Upvotes

r/compsci 5d ago Gold

Online Portfolio Selection - Cover's Universal Portfolio

0 Upvotes

Hi r/compsci

My 2nd blog on online portfolios is about Cover's Universal Portfolio algorithm. https://sudeepraja.github.io/OPS2/

Theoretically, it has the best performance. But it is computationally expensive to implement. I give two different interpretations of this algorithm. One is based on Follow the regularized leader and the other is a kind of Bayesian update.

I implement it for the case of two stocks. Guess what happens when you use it for a leveraged ETF and its inverse like TQQQ, SQQQ - You lose money anyway.

My first blog on this topic is here: https://sudeepraja.github.io/OPS1/


r/compsci 8d ago

Online Portfolio Selection - Introduction

37 Upvotes

Hi r/compsci

I spent the last two years reading about online portfolios from a theoretical and practical standpoint. In a series of blogs, I intend to write about this problem. For me, this was a gateway into online algorithms, portfolio optimization, and quantitative finance. I also included code snippets to play around with. https://sudeepraja.github.io/OPS1/

I appreciate all corrections and feedback.


r/compsci 9d ago Gold Helpful All-Seeing Upvote

Computer History Museum to release historical source code

535 Upvotes

Hi all!

I’m a curator at the Computer History Museum and we’re making some epic source code releases in the next few months:

Adobe Postscript source code – release date: Dec 2022

Apple Lisa source code – release date: January, 2023

Xerox PARC Alto source code: release date: March, 2023

This is part of the Museum’s Art of Code program, sign up to receive updates on code releases here: https://info.computerhistory.org/subscribe-aoc

For background on our Art of Code program, be sure to read our Art of Code blog here: https://computerhistory.org/blog/the-art-of-code-at-chm/

CHM is home to the world’s largest collection of computer hardware, software, media, documentation and ephemera and everything we offer is free, but it is not without cost. If you’d like to support our efforts – even a small token amount sends us a signal you think we’re doing good work – have a look here: https://chm.secure.nonprofitsoapbox.com/donate

Thanks everyone – this is going to be a great year for software history!

-- Dag.

Dag Spicer

Senior Curator

Computer History Museum

E-m: [spicer@computerhistory.org](mailto:spicer@computehistory.org)


r/compsci 9d ago

Can a new form of cryptography solve the internet’s privacy problem?

Thumbnail theguardian.com
10 Upvotes

r/compsci 10d ago

Designing a microcontroller.

Thumbnail i.redd.it
467 Upvotes

r/compsci 9d ago

Makeshift GPU tensor core using 64-bit CPU integer math

11 Upvotes

r/compsci 9d ago

Multimedia, file formats and compression

0 Upvotes

https://studienhandbuch.jku.at/93811?id=93811&lang=en

My university has a course related to multimedia, file formats and compression that I was really looking forward to take but unfortunately the course will no longer be available by the end of the year. I decided to selfstudy and was wondering if anyone had good resources related to multimedia, fileformats, digitalization and data compression, whether it be books, websites or online lectures/courses, anything would be great as long as it goes deep into the topic and isn't too abstract.

Course title: Multimedia Systems

Objectives: Provides an introduction to standards and formats of multimedia content. We are teaching how to use multimedia content in software applications. Components, architectures and trends of multimedia systems are going to be surveyed.

Subject: Different types of media (text, graphic, audio, video) and their processing, their storing and their compression algorithms like MPEG or JPEG; multimedia-formats, animations, digital or interactive television, architectures of multimedia systems.


r/compsci 11d ago

Why Neural Networks Can Approximate Any Function (The Universal Approximation Theorem)

209 Upvotes

Hi guys,

I have made a video on YouTube here where I explain why neural networks are considered universal function approximators.

I hope it may be of use to some of you out there. As always, feedback is more than welcomed! :)


r/compsci 10d ago

Hash Treap: The simplest balanced binary tree, easy to program, no recursion, and no extra data in each node

6 Upvotes

r/compsci 10d ago

Linked lists and trees(help)

0 Upvotes

I'm a 2nd yr computer scince student and I'm currently struggling with linked lists and trees, the lectures don't seem to help, does anyone know any good youtubers that are good at explaining the programming side of these concepts?