Drawing Automata and the History of Computer Science

January 29, 2018 nouyang

Note: This is mostly for me to remind myself of the name of the drawing automata that I still love to look at videos of and wonder at how amazing it is.

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

Currently I’m taking this Computer Science 191: Classics of Computer Science, where we read a bunch of famous papers tracing the evolution of computer science.

Today we talked about the Analytical Engine. (Lovelace wrote the lengthy “Notes” part which takes up the bottom 2/3). Some people at my table thought it was crazy to go from an abacus to this complicated setup. Due to my interest in mechanical engineering and robot art, I knew of this mechanical writing machine where you could slot letters in and out. I thought this was Maillardet’s (so 40 years before Babbage), but I think the letter-selecting device is actually from Jaquet-Droz automata.

The video I remember is the BBC one.

Anyhow, these were made to sell more watches (at least according to wikipeida)! Just some bored watchmakers, making crazy intense automata.

Here is another documentary which explains in the first 5 minutes or so how Jaquet made little dioramas with mechanically spinning and quacking birds (really, reminds me of the Fabergé eggs!), traveled and got a bunch of money after waiting months to see a king, and then got to go make complicated things like this automata.

jacquard

Maillardet’s is at the Franklin Institute in Philadelphia. Here is some more about it from FI. Here’s a CBS show about it. Apparently it is possible it has the most “read-only memory”, about 300 kb.

Also apparently the drawing automata in Hugo was created in real life! This pleases me immensely.

Oh yea they also passed around some Jacquard’s loom punchcards. I don’t know much about weaving and so the complexity of programmable looms goes over my head, but I think the drawing automata makes it really easy to comprehend how complicated these things can get. At least, it really impressed the folks at my table 🙂

What else… oh I learned what squaring the circle means, since Hilbert talks about it in his “Mathematical Problems” lecture.

I also love how the wikipedia article talks about “debunking illogical circle-squaring theories“. I guess we have perpetual motion theories still! Apparently “squaring the circle” is also an idiom for “trying to do the impossible.”

Oh, and there’s a lady mathematician who formed an integral part of the 10th problem, which is the one people go gaga about trying to figure out if Hilbert would have approved of (the solution to). That’s the one where we learned that we cannot know the solution

I also thought it was cool how the work to solve this problem built up over two decades. (and one of the four contributors was Julia Robinson, who had a J.R. hypothesis that wasn’t proven until 20 years later).

Oh, and then we read Turing’s paper, the one with That Word. Entscheidungsproblem. Anyhow, I started browsing briefly and decided I really still have no idea what it means for something to be computable. The wikipedia article states “Computability is the ability to solve a problem in an effective manner”. Really, wikipedia? It’s probably similar to the question of what counts as a robot, I suppose. Anyhow, that article briefly mentions both automata (heh, sounds like automaton) and also hypercomputability. Such a fun word.

Okay, now back to fixing the problem of why my alarm clock app, Timely, no longer goes off reliably :((((((((((( I thought Timely might have updated, but it says the last update was in September of 2017. So maybe it’s some Tmobile or Android or Samsung update that borked my alarm clock 🙁 I’ll try the only other version of Timely, a 2015 update, and report back.

Uncategorized

connecting to eduroam & harvard wireless without having to install sketchy things

January 26, 2018 nouyang 2 Comments

UPDATE 27 SEPT 2019 (checked current as of 27 Dec 2019 as well) – Ubuntu 19.04 / Android version 9

It appears eduroam settings have changed (CA certificate *must* be installed)

On my laptop (Ubuntu 19.04)

Where the CA file comes from

 /etc/ssl/certs/AddTrust_External_Root.pem

(thanks old blog post)

Note: Eduroam appears to be the same settings as Harvard Secure

Android

I also had to install the certs on my phone

Put above file onto phone (I transferred using bluetooth> send files, but usb would work too I’m sure)
Install on phone
And then type some sensible name
Then, connect to Harvard Secure wifi with similar settings as in the desktop case. Select the CA certificate we just installed.

And hopefully it will work.

PROTIP: You have to be fully disconnect from the network (not attempting to connect to it) in order to edit the settings.

I’m still working out how to reconnect to eduroam… sigh

Legitimately, when I have friends co-work, it’s so annoying for them to connect to the internet that I end up just giving them my password. Which is wrong and bad for all kinds of reasons, but that’s life as an end-user…

Troubleshooting / via CLI for the nerds

rui@chaiX1YG2:/ $ nmcli con 
NAME UUID TYPE DEVICE 
eduroam 9196d2be-df9e-4f92-8781-c5c47c60e90d wifi wlp4s0

rui@chaiX1YG2:/etc/NetworkManager/system-connections$ $ sudo cat eduroam
[sudo] password for rui: 
[connection]
id=eduroam
uuid=9196d2be-df9e-4f92-8781-c5c47c60e90d
type=wifi
permissions=
timestamp=1548391592

[wifi]
mac-address=A0:AF:BD:E9:F4:18
mac-address-blacklist=
mode=infrastructure
seen-bssids=A4:6C:3B:3F:AA:FB;70:3A:0E:88:80:50
ssid=eduroam

[wifi-security]
key-mgmt=wpa-eap

[802-1x]
ca-cert=/etc/ssl/certs/AddTrust_External_Root.pem
eap=ttls;
identity=CHANGETHIS@g.harvard.edu
password=CHANGETHIS
phase2-auth=pap

[ipv4]
dns-search=
method=auto

[ipv6]
addr-gen-mode=stable-privacy
dns-search=
method=auto

OUTDATED – Old post below:

Harvard is very insistent about me downloading random software in order to connect to their wireless network, even though I have Harvard credentials (and eduroam credentials).

I have no idea why they do this. Why do I need to download software to connect to a wifi network? Anyhow, the solution is to just ignore it and figure out the settings on my own.

I just use eduroam. Here is what the internet told me:

https://superuser.com/questions/34198/securew2-equivalent-on-linux#472303

Security : WPA & WPA2 Enterprise

Authentication : Tunnelled TLS

Anonymous Identity : (I left this blank,but I think they have configured the network that way so it won’t ask for this kind of Identity)

CA certificate : (I left this blank as well,but again this has to do with the configuration of the wireless network,so it might be different in other educational institutes)

Inner Authentication : PAP

Username : (the one given from your school)

Password : (the one given from your school)

android

Identity & password = my harvard credentials.

windows

Right now I am using Windows 10, and I have discovered that the wireless situation is not really better and maybe somewhat worse than on Ubuntu. *sigh*

Anyhow, I had expired MIT credentials. I finally figured out how to change my password: Go to settings -> Wifi -> Manage known networks (this option is kind of hard to see) -> eduroam -> Forget.

(Jeebus knows why “properties” doesn’t tell me / let me do anything useful)

Then, the next time I click on “eduroam” and “Connect”, it will prompt me for a username and password. Enter in my harvard credentials and voila.

Uncategorized

pom poms galore

January 2, 2018 nouyang 1 Comment

poms poms? those things cheerleaders wave around?

Kind of, but made of yarn!

neko_cat — one of the first pom poms i ever made!

i was looking at some knitting blog, when i was interested in making open source versions of textile manufacturing machines, and the author briefly mentioned trying to find a book for sale by trikotri. as i’m familiar with chinese / hanzi characters, i was able to find it easily on ebay.

(if you mispell their name, by the way, you end up with pictures of tractors! I remember their name as “trick or try” now).

some inspiration

since then, making pom poms has grown into an obsession… in particular, I wanted to try to figure out how this tiger was made

Wow, right?? That’s one intensely detailed pompom.

Okay, so how do you make these cute fluffy things?
They’re actually pretty straightforward, essentially you make a dense loops of yarn and then tie a tight knot around the center, then cut through the tops and bottoms of the loops, and voila, you have a yarn pom pom.

quickstart

Watch this video. She uses cardboard to make the “pom pom tool”. Note in particular that with the custom tool, she can make elliptical instead of spherical pom poms (though you can always shave spherical ones into elliptical ones, of course).

That should give you an idea of how to “customize” a pom pom.

If you just want to make gifts for friends, that’s it! Cut out some eyes, ears, and a mouth from felt, and in ten minutes you’ve created a really adorable gift that doesn’t take up much space. There’s ZERO need to make more detailed designs, the cute ones are simple and will be adored.

a step up — flowers

but then… how to make the more detailed designs?

After some searching, I finally came across a tutorial online (since then I’ve found several books that also cover the topic!) by https://mrprintables.com.

Specifically, he shows in his Flower Pom Poms article how to go about designing a pom pom (again using a home-made cardboard tool).

Essentially, the way we make pom poms is symmetrical (I’m still trying to figure out how asymmetrical designs work, though maybe they all are just by using tweezers to fiddle the yarn around…). The things to consider are where you are wrapping, and how “deep” (how many loops) you are wrapping, and what “layer” you are wrapping (on top or under what other layers). Succinctly, here is the main ideas from the blog.

Take the flower design you want, and find the axis of symmetry.

Next, we see that we start out by wrapping the innermost layer, #1 (yellow). Next, we wrap the red layer, #2, around it. Then we wrap the green layer, #3, around that — but note that we don’t want the green part to not completely overlap the red part, and wrap accordingly. Finally, we finish off with a white layer. This is just half of the pom pom — the back half is made by doing a full white layer of similar thickness.

credit to https://mrprintables.com/blog/making-flower-pom-poms-diy-pom-pom-maker/

here we can see the flower design after it is cut out.

Next step — alphabet

Okay, so now maybe we want to go even more detailed with the pom poms. Flowers are great, but what about the alphabet?

Mr. Printables shows us the way again.

alphabet-pompoms-tutorial-hello — more magic! credit to my printables https://mrprintables.com/blog/alphabet-pompoms-tutorial/

I spent many hours on my “ABC”s of pom pom making!

The “A” is quite instructive on how to think about this.

pompom_alphabet_failures_aaaaaa — a bunch of my failures…

I struggled a lot!! with keeping the yarn threads from slipping off of each other, and have the A come out with the bottom legs stuck together (more like an eye-shape than an “A”), and a lot of other problems.

how-to-make-pompom-A-step1 — mr printables version

I think part of it is the yarn I used, so I have to look into that, as I don’t know anything about the different types of yarn. On the leftmost pom pom you can clearly see that the “denim yarn” I got was not suitable. And I’d try to put too many winds on, so I couldn’t close the pom pom maker (I got some clover pom pom makers). Or the letters weren’t consistently fat. Or the letters were falling off the edges of the pom pom. I’m really not sure… I should try it with bigger pom poms, maybe that’d make life easier.

I think in the end, the key is to not be too perfectionist… and to be okay with using tweezers and scissors to “post-process” your pom poms!

Asymmetry

It turns out that the dirty little trick is to make the “asymmetrical” letters like “F” and “P” and “S” still symmetric by having a reversed (mirror) version of the letter on the other side. The symmetry is created by carving the letter into two parts and mirroring those parts individually.

Full listing of Mr. Printables pom pom posts:

Flowers

Alphabet

Fruit

Halloween

Oh nice, here’s a tutorial showing how they made it! Notably it looks like their pom poms are a lot bigger than what I was going for! So maybe that accounts for how easy they had it. Also, they do say 20-30 minutes per pom pom… I feel like I can rest easier now.

How To Make A Ghost Pom Pom

the secret to trikotri ‘s pom poms!

Some months (a year?) later, trikotri put up a youtube video of how she makes her pom poms.

My puzzlement was over not just the intricacy of her tiger pom poms, but also the asymmetry in some of her pom poms

It turns out to be a combination of pom poms and felting!

Perhaps the tiger’s asymmetrical features are made by poking wool in to make the stripes? I will have to try to make the tiger!

pom pom parties

okay, that was an info dump about how *other* people make pom poms. What about the beginner stuff — what you can make in 2 or 3 hours?

You can definitely make a lot and get really far! I organized a pom pom party where I got a bunch of friends together and we all made pom poms, everyone except me for the first time.

Doing so is easy, just bring colors of yarn, sharp scissors (!! This is important, probably at least 1 pair of scissors per two people, and they need to be sharp). If you want to be fancy, bring hot glue, googly eyes, and felt (for ears, mouths, etc.) (note — I got a variety pack of felt on amazon, that didn’t include white and black! so be careful what you get).

My friend Renee Bell did too! Here are the creations of some of her friends.

About the teddy bear — http://maths.mit.edu/~nacho/ Nacho Bell pom pom . From the website: “In Fall 2015, I tried to teach 18.01 (single-variable calculus). However, since I have no fingers, I could not pick up the chalk, and consequently got very poor reviews.”