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Ralsina.Me — Roberto Alsina's website

My first interesting hack

In the pre­vi­ous ar­ti­cle, some­one sug­gest­ed cheat­ing on ex­ams as an in­ter­est­ing ap­pli­ca­tion of telepa­thy.

Which re­mind­ed me of my first in­ter­est­ing hack.

I was in col­lege, back when com­put­er time was al­lo­cat­ed by the hour, and I had no com­put­er, and I was about to take my fi­nal ex­am on lin­ear pro­gram­ming.

For those who are not fa­mil­iar with the term, lin­ear pro­gram­ming is not re­al­ly about pro­gram­ming. It's about solv­ing a spe­cif­ic ind of op­ti­miza­tion prob­lem­s.

And for those who don't know that, don't swaet it, it re­duced, in re­al 1989 life, to ap­ply­ing a pro­gram called LIN­DO to find a lo­cal or glob­al min or max for a func­tion.

Now, we were a poor col­lege, so there were like 10 com­put­er­s. For 5000 stu­dents. And we, in that sub­jec­t, were not al­lowed to use it.

And it did­n't have lin­ear pro­gram­ming soft­ware in it any­way. And it had no com­pil­ers or in­ter­preters (ex­cept qba­sic).

So, we did LIN­DO by hand. On pa­per (the Sim­plex method­).

And it was bor­ing. But we did it. It is pret­ty sim­ple once you get the hang of it. But you have to make hun­dreds of cal­cu­la­tion­s, so we were al­lowed cal­cu­la­tors.

And I had this ba­by.

I had bought it with my sec­ond pay­check as a teach­er as­sis­tan­t. It cost­ed me about the same as a small bike.

Or a TV.

And it had 4KB of ram, an ascii key­board, and 116 pre­loaded pro­grams for com­mon sci­en­tif­ic cal­cu­la­tion.

It was the best cal­cu­la­tor I ev­er had :-)

And it was pro­gram­mable in BA­SIC.

So, the night be­fore the ex­am, as I did a sam­ple drill, I de­cid­ed to im­ple­ment a solver.

But since we had to solve things on pa­per, I had to show in­ter­me­di­ate step­s.

So, in­stead of a pro­gram to solve the prob­lem, I wrote a pro­gram that solved step-by-step as done by hand. Which was about 20x hard­er.

And it did fit and run in the 4KB of ram, and it dis­played the in­ter­me­di­ate re­sults on the 2x32 char screen.

Sad­ly, there was no way to take a pro­gram out of it, so it was lost on the next bat­tery change.

But hey, I think that was nice :-)

Telepathy. Why?

I saw Penn & Teller's show about ESP last night. Be­sides be­ing hi­lar­i­ous, a throw­away com­ment (by Pen­n, of course) made me think.

Here's what he said (give or take a word):

Telepa­thy is com­mu­ni­cat­ing your thoughts di­rect­ly to some­one else's brain. Be­cause it seems talk­ing is too much work.

And it got me think­ing... why would any­one want to be a telepath? What's the prac­ti­cal pur­pose of telepa­thy?

In this anec­dote I see one of the two prob­lems with telepa­thy. The fact that it's not nec­es­sary.

It's sup­posed to be a mech­a­nism for com­mu­ni­ca­tion. Well, as Penn said, you can talk, so there are al­ter­na­tives. There must be a com­pelling rea­son why telepa­thy would be bet­ter. Let's con­sid­er some pa­ram­e­ters of com­mu­ni­ca­tion qual­i­ty!

  • Re­li­a­­bil­i­­ty of con­nec­­tion

I don't ex­pect any­one will tell me telepa­thy is more re­li­able than a cell phone. At least not in the forms ESP re­search has any hope of find­ing.

If there were a re­al­ly re­li­able telepath, he would have been found al­ready. Un­less he knows he's been sought, and us­es his telepa­thy to hide him­self ;-)

  • Range

Well... let's look at the al­ter­na­tive! Satel­lite phones. They work (worked?) any­where on earth. Sure­ly telepa­thy's ad­van­tage over that would be marginal? And Irid­i­um went bankrup­t, so there was not much de­mand for that, ei­ther.

  • Re­li­a­­bil­i­­ty of sig­­nal

By this I mean the odds of get­ting what the oth­er guy is send­ing.

I sup­pose if telepaths trans­mit the thought in its raw for­m, in­ter­pret­ing it on the oth­er side is go­ing to be quite hard.

Take me, for ex­am­ple. As a side ef­fect of how I learnt en­glish, al­most ev­ery con­scious thought I have is in my head in span­ish and in eng­lish. At the same time.

I lit­er­al­ly have eng­lish dub­bing run­ning full­time in my head. That's got­ta be an­noy­ing!

Even with­out that, it takes me some ef­fort to un­der­stand what I'm think­ing. And I re­al­ly know me!

Please sug­gest oth­er para­menters in the com­ments if you wan­t!

Now, I have a strong sus­pi­cion about why peo­ple want to be­lieve in telepa­thy, and I think they fall in two camp­s.

  • Those who want to read what you think with­­out you know­ing it (or in­­ten­­tion­al­­ly shar­ing it).

This is some sort of puerile voyeuris­tic fan­ta­sy, like dream­ing of be­ing in­vis­i­ble (y­ou know why they want that, right? ;-)

Prob­a­bly the rea­son why the US gov­ern­ment used to throw away mon­ey pay­ing ESP re­searcher­s.

  • The patho­log­i­­cal­­ly shy

They want you to re­al­ly un­der­stand what they think, so you will un­der­stand and like and love them.

Well, that's all find and dandy, but it's per­haps eas­i­er to ac­tu­al­ly ex­press your­self in­stead of dream­ing about hav­ing a ESP ca­pa­bil­i­ty you will nev­er have?

I feel some ten­der­ness for these mal­ad­just­ed guys, most­ly be­cause I used to be one, and I still am in some ways.

But I have learned a few things since then. No, they will not like you if they un­der­stand you. Or maybe yes. But it's not guar­an­teed. So, be a nicer guy in­stead of dream­ing of telepa­thy. Start un­der­stand­ing them, even!

Warn­ing, sil­ly pseu­do-bud­dhist anec­dote:

The Bud­dha saw one of his dis­ci­ples cross a riv­er walk­ing over the wa­ter. He con­grat­u­lat­ed him, then gave the dis­ci­ple a coin and told him: use this to pay the fer­ry­man next time.

A mir­a­cle that on­ly does the same you get for a coin is a mir­a­cle that's worth a coin.

Telepa­thy is a mir­a­cle worth 20 bucks a month for 500 min­utes or what­ev­er your cell plan is.

Marriage bureaucracy

Rosario and I are pret­ty much non-­be­liev­er­s, so we are get­ting mar­ried on­ly with a civ­il cer­e­mo­ny (which is manda­to­ry any­way).

So, this morn­ing we went to the Reg­istro Civ­il to ar­range the ap­point­ment for the wed­ding.

Ev­ery­thing was done pret­ty quick­ly, no fuss, good vibes from the la­dy who's mar­ry­ing us, we were pret­ty hap­py. But one thing called our at­ten­tion.

We had to wait for about 30 min­utes to set the ap­point­ment be­cause we were the third cou­ple.

There were we (dressed... per­haps too ca­su­al­ly. This is just bu­reau­cra­cy and it was ear­ly in the morn­ing ;-)

An­oth­er cou­ple of about 35/40 year-olds dressed very nice­ly, good clothes, nice shoes (we do live in a pret­ty fan­cy neigh­bor­hood).

And the last one were in their twen­ties, good look­ing peo­ple.

Now, the three cou­ples were per­form­ing a nec­es­sary and pret­ty crit­i­cal step in get­ting mar­ried, it's not ro­man­tic at al­l, but af­ter you put your fin­ger­print in the re­quest, you are say­ing that you are re­al­ly go­ing to get mar­ried.

And any­way, we were all ak­ing for dates in the next mon­th, so we were all pret­ty close to get­ting mar­rried.

And you know what, I was there, hold­ing Rosar­i­o's hand, we were talk­ing about how much we want­ed to fi­nal­ly get all this done and be a "le­gal" cou­ple, hug­ging and kiss­ing (noth­ing scan­dalous ;-)... the oth­er two cou­ples hard­ly talked to each oth­er.

The old­er ones, I think the guy on­ly said "this is tak­ing a while" and she an­swered with a nod.

What the hel­l? I was think­ing about start­ing to scream at them you are all go­ing to be ex­treme­ly un­hap­py!!! do not get mar­ried if you don't like each oth­er!!!*

Then again, per­haps they had made the wrong line and were wait­ing for death cer­tifi­cates?

I mean, why the heck were they get­ting mar­ried?

First piece of my "distro"

Here are runit RPM and SRPM for Cen­tOS 4.2 (prob­a­bly works on some oth­er dis­tros as well).

You install it, then clone your GRUB (or LILO) entry so you boot passing init=/s­bin/runit-init to the kernel and when you boot it, it should start on a rather normal-looking runlevel 3.

To re­boot or halt, use re­boot-runit and halt-runit, please!

Keep in mind that this is just a be­gin­ning, since all your ser­vices (ex­cept your ttys :-) are still run­ning with­out su­per­vi­sion!

Should not de­stroy any­thing, but use at your own risk.

You will have to work fur­ther if you want to do more.

Included is /etc/runit/services/test a trivial template service.

Sor­ry about the spam­my host­ing, but I will get a de­cent serv­er space for these files some­where even­tu­al­ly. These rpms are just a teaser, any­way :-)

I am getting married.

  • Date? Feb. 18th. 2006

  • Where? San Isidro, Buenos Aires, Ar­­gen­ti­­na.

  • Who? Rosario Guer­rero + Rober­­to Al­si­­na

  • Why? Be­­cause we love each oth­­er.

Look at this pic­ture.

Yes, it's what it looks like. It's part of our wed­ding in­vi­ta­tion­s. How nerdy is that, ex­act­ly?

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