Hacker News Reader

dododoon False Dichotomies in Convertible Note vs Equity Seed Rounds

am i correct in thinking that convertible notes can be thought of as a way of changing the equilibrium of prisoner's dilemma? i.e., by introducing a temporal element and rewarding early investors you avoid the equilibrium where everyone is waiting for everyone else (akin to the Nash equilibrium of prisoner's dilemma where both prisoners stay silent, instead you want both prisoner's to confess).

dododoon Compromising Twitter's OAuth security system

the DRM-like application keys leads to some obvious underhand scenarios.

if the app key is compromised, the key is revoked and no twitter access. if you extract the twitter oauth key from a competitor's desktop/android/iphone/etc app and post it on the internet, twitter will kill your competitors twitter application until they distribute a new key. rinse + repeat.

i wonder if twitter will revoke their own app key.

dododoon Ping: It's even worse than it appeared

and you're not worried by CBS-owned last.fm or spotify? they seem very similar. what's the difference? i couldn't find anything on the page that convinced me to switch or use in addition to these.

p.s., those side-sticking things are really annoying.

dododoon Build An Opensource Dropbox Clone

lsyncd does the brunt of the work. it uses inotify, which is a facility of the linux kernel, to tell which files should be copied. but i think there is a problem.

inotify is not guaranteed to see every file system access. in fact, it often misses them when the file system is busy because there is an upper bound upon the number of inotify events that can be queued, set in /proc/sys/fs/inotify/max_queued_events.

i.e., you could get data loss using this mechanism alone. you need to also run rsync every so often, i think.

the lsyncd guys are aware of this: http://code.google.com/p/lsyncd/

(maybe this is how dropbox works under linux too, if so it presumably has the same problem..)

dododoon 100 Prisoners, 100 lines of code

with 2 prisoners the probability of success is 0.5, so you are correct.

with 4 prisoners the probability of success is about 0.37, which is better than chance. (the probability of success turns out to be one minus the difference of two harmonic numbers.)

it's hard to give a hint without giving the answer. the best i can do is that it has to do with the structure of cycles in permutations.

dododoon Heavy drinkers outlive nondrinkers

they used self-reported but cite four studies case where in slightly older populations self-reporting is deemed accurate.

see section "Materials and methods" subsection "Baseline Alcohol consumption" in the linked paper.

dododoon Heavy drinkers outlive nondrinkers

title of paper is: "Late-life alcohol consumption and 20-Year mortality" http://onlinelibrary.wiley.com/store/10.1111/j.1530-0277.201...

in particular, they are looking whether some 55-65 year olds died the next 20 years, women were underrepresented in their sample (just 37%) who tend to be lighter drinkers anyhow [citation needed]. participants were select by having been at a health care facility in the last 3 years. the socioeconomic factors they took into account where those at the start ("at baseline"). i.e., who knows what changed in the past or future, or why they were in a health care center, etc. was there an observation effect? who knows.

the yahoo article doesn't seem to represent this very well. hype hype hype

dododoon Two pieces of code someone really ought to write

awk has something similar too:

  The following special filenames may be used with the |&
  co-process operator for creating TCP/IP network connections.

  /inet/tcp/lport/rhost/rport  File for TCP/IP connection 
  on local port lport to remote host rhost on remote port 
  rport.  Use a port of 0 to have the system pick a port.

dododoon Linux Kernel Based Virtual Machine

i surmise it's the rate at which an article/comment gets points that determines its ranking.

dododoon Google Acquires Angstro, a Social Networking Start-Up

http://www.googlelabs.com/?status=graduated

and to come:

http://www.googlelabs.com/

dododoon Ask HN: What's up with all these services charging $10/$15 a month?

average cable bill in the US in 2008 was $71. http://www.multichannel.com/article/196364-Study_Average_Cab...

increases since then seems to be 5-7% per year.

good guess!

dododoon Elementary Number Theory

the content of this book is a little odd: it seems narrowly oriented towards getting enough number theory to understand RSA, Diffie-Hellman, and elliptic curve cryptography.

i very much enjoy a book with the same title but by burton:

http://www.mcgraw-hill.co.uk/html/0071244255.html

it contains a lot more of number theory and a little cryptography too.

dododoon Linux: Understanding File Descriptors and IO Redirection

instead of /proc/PID/fd/XX you can simply use /proc/self/fd/XX if PID is simply the pid of the current process.

standard input/output/error are not necessarily character devices (as stated in the article). they can be anything (sockets, files, etc).

dododoon Homeless Experiment

george orwell (who also wrote 1984) conducted a similar experiment in the late 1920s and wrote a book about it:

http://en.wikipedia.org/wiki/Down_and_Out_in_Paris_and_Londo...

dododoon Futurama Writer Created And Proved A Brand New Math Theorem Just For Episode

i'm not sure what you mean by discrete.

SO(3) (the group of rotations) is not discrete in any sense i can think of.

some groups have a discrete topology, but not all by any means... are you referring to cayley's theorem?

dododoon How does mkdir() really work?

oh? on a recent glibc:

  $ objdump -D /lib/libc.so.6 | grep 'int[[:space:]]*$0x80' | wc -l
  447

what were you thinking they used instead? sysenter? iirc, this turns out to be slower than "int $0x80."

dododoon How does mkdir() really work?

1. the system call table of linux and minix are very different. posix specifies the minimum interface (and i don't think it specifies what is and what is not a system call). linux has a lot more system calls than minix. the system call table itself changes between architectures under linux since...

2. linux duplicates the system call dispatch table for each architecture. check it out:

http://lxr.linux.no/linux+v2.6.35/arch/x86/ia32/ia32entry.S#...

http://lxr.linux.no/linux+v2.6.35/arch/avr32/kernel/syscall_...

whereas NetBSD has no such duplication. in fact, one complaint about the linux kernel is that it has too much per-architecture code.

3. who uses minix? the linux kernel is actually not too bad. ctags is your friend. i learnt on linux+netbsd, it's not really as bad as people make out.

dododoon How does mkdir() really work?

linux was initially designed for just x86. that's the real reason it's complicated in this case: each architecture defines it's own system call table and dispatch, for example, instead of having a common one amongst architectures.

other kernels (like NetBSD) where designed with being portable across architectures in mind and so have much cleaner code paths (typically just one system call table and the bare minimum arch specific code to link it all together).

minix is okay but it's not really going to give you a grip on a real work kernel. "design and implementation of 4.4BSD-lite" is a really good book for this: most BSDs are very similar to this design still in a lot of ways, and many of the ideas described (e.g., VFS) are also used in linux.

dododoon Infer: Inference and Machine Learning in Clojure

i used Infer.NET: buggy as anything, horrible syntax. it's for doing inference in graphical models using EP; these are the same techniques as those MS use for trueskill.

this (Infer) looks like it's for a different kind of inference: classification (essentially linear, but with a few bells and whistles).

(not graphical models right now; probabilities.clj is very much lacking.)

dododoon Intel to buy McAfee for $7.7 Billion

there's already a lot of hardware-based "security" out there. for example:

* http://en.wikipedia.org/wiki/Trusted_Platform_Module

* http://www.intel.com/technology/anti-theft/

* http://en.wikipedia.org/wiki/NX_bit

and so on, of which Intel is currently involved with lots.

Security is what a desktop processor spends a lot of it's time doing: making sure programs are isolated from one another and the kernel whilst still executing code.

dododoon Intel to buy McAfee for $7.7 Billion

McAfee do more than just desktop antivirus: for example, they have mobile, virtualisation and network security products. see products by category here: http://www.mcafee.com/uk/enterprise/index.html

Intel has a large interest in mobile, virtualisation and network arenas; this isn't really as surprising as you make out.

dododoon Don’t let jQuery’s $(document).ready() slow you down

the rest seems to be summarised as: don't wait for things you don't need to wait for.

$(document).ready() can be a bit of a sledgehammer in terms of latency.

dododoon Email sucks. Time saving tips from Kevin Rose

correction to tip #2: the plus trick (username+foo@example.org) works with many mail systems not just gmail (as stated). its origins predate gmail.

correction to tip #4: iPhone's append "Sent from my iPhone" not "Sent from iPhone". i'd notice the missing "my". "Sent from my mobile." is just fine and probably a better approach.

dododoon Eric Schmidt On the Future of Search

instead of telling me what to do, i'd much rather google helped me make informed choices about what to do.

dododoon How Oracle might kill Google’s Android and software patents all at once

people keep citing btrfs. oracle could still kill this: it conflicts with ZFS and presumably oracle now owns patents in this domain too.

dododoon 25 Best Hangman Words

i find often even if you don't know the word, you know something about, for example, the phoneme structure of words, which allows you to guess.

it's not just it's not known, but also it has an uncommon composition.

for example, you may not know what the solution to abapi_al is exactly, but reasoning phoenetically should get it quickly.

dododoon 25 Best Hangman Words

my favourite hangman word is tmesis. i'm yet to lose a game with it. it works well psychologically: people very quickly get to t_esis (e and t being the most common letters) but m takes too long: although m is common, tmesis is the only word in the english language that starts like this.

dododoon Shut up and ship

which machine learning algorithms is causata shipping to customers? i could not find this (nor the fact you were shipping) from the causata website.

you wrote:

Alas, the Haystack web site has zero technical details.

the causata web site appears to be equally placed.

dododoon Shut up and ship

many companies build up the hype before they ship. isn't that just marketing?

i call hypocrisy. jgrahamc is involved with causata: check out their website.

http://www.causata.com/

count the number of times you read:

"This has to change. Stay tuned for more details."

where are the products? what have they shipped?