# Zendo-like Induction Game for Playing Online

I re­cently en­coun­tered the in­duc­tive logic game Zendo 1, and it looks like a great game for as­piring ra­tio­nal­ists. I’d like to play a game like it among the peo­ple on this fo­rum. How­ever, Zendo is very vi­sual, with an em­pha­sis on color and po­si­tion of pieces, so it would be difficult to play over the In­ter­net. So I’ve adapted the con­cept and rules of Zendo to a for­mat that can be played in an LW thread.

The ba­sic premise of Zendo is that of try­ing to figure out a rule by ob­serv­ing which en­tities do or do not com­ply with it. One player, the “Master,” de­vises a rule and pre­sents one struc­ture that does and one that does not com­ply. In the on­line ver­sion, these are strings of 1-digit num­bers. For in­stance, the rule might be “at least 2 of the digits are odd.” Then “2 5 1 0 ” would satisfy the rule, and “8 3 2” would not. The rule can be any level of com­plex­ity and may con­cern any­thing about the num­bers, like “The string must con­tain at least 4 digits” or “The sum of the first two digits must be greater than the sum of the last two” or what­ever. It may not con­cern any­thing other than the string, such as the times­tamp of the post.

Play­ers take turns by propos­ing a string in re­ply to the com­ment with the first two strings, and say­ing ei­ther “Master” or “Mondo”. If the player says “Master,” the Master will re­ply to the com­ment con­tain­ing the string and say “yes” if it com­plies with the rule and “no” if it does not. If the player says “Mondo,” all play­ers have some amount of time to post a re­ply guess­ing whether or not the string will meet the rule be­fore the Master judges it. Cur­rently this time is 8 hours so ev­ery­one will have time to see it, but if this seems too long it can be short­ened. Tra­di­tion­ally this is done by con­ceal­ing a col­ored stone in one’s hand with no­body see­ing any­body else’s guess un­til time is up, so if you want post your guess in rot13 sur­rounded by gob­bledy­gook (e.g. fyqxws­fyxqw­st­fyxlrffyqxwsyfqxwtsfy). Please don’t read other peo­ple’s rot13. At the end of the time pe­riod, the Master will judge the string and give ev­ery­one who guessed cor­rectly a guess­ing point.

At the end of your turn, af­ter your string has been judged, you may spend one guess­ing point to re­ply to the “Guess the rule here.” com­ment and guess the rule. The Master may ask clar­ify­ing ques­tions about am­bi­gui­ties in the guess. When the Master is satis­fied that e un­der­stands the guess, e will ei­ther pro­nounce the guesser the win­ner or provide a string satis­fy­ing the guess but not the true rule or vice versa. The guesser may guess un­til e wins or runs out of guess­ing points.

I’ve de­cided an ini­tial rule, and started a game in the com­ments. To join the game, re­ply to the com­ment con­tain­ing the first two strings. To com­ment on the mer­its or prob­lems of the game, say that this shouldn’t have been posted, ask ques­tions, or sug­gest changes to the rules, re­ply to “Meta stuff goes here.”

1: The link is bro­ken. It’s sup­posed to go to http://​​en.wikipe­dia.org/​​wiki/​​Zendo_%28game%29 .

EDIT: The first game was fun, but time differ­ences made it a bit chaotic. The sec­ond game will be at­tempted on IRC chat. To join, sug­gest a time, or vol­un­teer to be Master, post a com­ment to that effect.

• I en­dorse mov­ing the ac­tual turn-tak­ing me­chan­ics onto an­other fo­rum. I’m all for peo­ple hav­ing fun, but this mechanism gen­er­ates an as­ton­ish­ing num­ber of re­ally re­ally un­in­ter­est­ing com­ments in ex­change, and I don’t think the cost is worth it.

• Yeah, I no­ticed the state of the re­cent com­ments sec­tion my­self. Sorry.

• If you want to try play­ing reg­u­lar ex­pres­sion Zendo against the com­puter, I have a JavaScript ver­sion here:

https://​​codewiz.org/​​~scubed/​​rezendo/​​rezendo.html

That way you can get im­me­di­ate feed­back.

• As of this com­ment, I am go­ing to sleep. I will be back to­mor­row. Any­one in an­other time zone, carry on and I’ll judge ev­ery­thing to­mor­row.

On an­other note, I’ve been pleased with the re­sponse this has gen­er­ated and am en­joy­ing the game. I hope ev­ery­one else is too.

• I love Zendo! I also don’t want to hold up the turns, so I’d like to play and promise not to post more than one guess per round.

Mondo, 3, I pre­dict yes is the an­swer.

• This string is no. Ben­quo gets a guess­ing point.

• klkrkfk

• fqsstuabstugi

• fqsstuabstugi

• Wel­come! Your guess will be judged… some­time in the fu­ture. Be­fore noon EST to­mor­row. I’m mov­ing your guess to the guess thread so they’re all in the same place.

• I love Zendo! I also don’t want to hold up the turns, so I’d like to play and promise not to post more than one guess per round.

Mondo, 3, yes.

• Cur­rent turn list: Ben­quo, Larks, cata. Other peo­ple can still join.

ETA: Cur­rently Larks’s turn.

• I posted, but feel free to leave me out of the turn struc­ture—I feel that hav­ing less turns isn’t a big deal (at least, un­til a lot of data has been col­lected, and we’re guess­ing the rule.)

• Master 6 2 5 2

• I don’t know if you’ve seen the turn list yet. In case you haven’t, it’s your turn.

• I want ev­ery­one to have easy ac­cess to all the pre­vi­ous guesses, so I’m mov­ing this to the game sub­thread.

• Meta stuff goes here.

• One is­sue with Zendo that doesn’t nec­es­sar­ily make it a great game for ac­tu­ally im­prov­ing ra­tio­nal­ity is that the rules are made by hu­mans, so you can use psy­chol­ogy to get in­for­ma­tion. For ex­am­ple, I was play­ing with my fam­ily a few nights ago and my mother guessed a cer­tain rule, my lit­tle brother im­me­di­ately said “That’s not Josh’s rule. it isn’t el­e­gant.” And sneak­ier play­ers can do even worse stuff us­ing sidechan­nel at­tacks. In par­tic­u­lar, how long it takes for the Master to judge whether differ­ent con­figu­ra­tions fit the rule can give a lot of in­for­ma­tion about the rule form.

• Aren’t those all just ad­di­tional as­pects of the game, ad­di­tional con­straints in the op­ti­miza­tion pro­cess?

If peo­ple will make in­fer­ences from how long the Master takes to judge whether differ­ent con­figu­ra­tions fit the rule, then the Master should ei­ther sys­tem­at­i­cally ma­nipu­late his times to give the wrong im­pres­sion or in­tro­duce some ran­dom waits. And if you are known for only us­ing el­e­gant rules, then you’re us­ing a sub-op­ti­mal strat­egy for choos­ing the pat­terns, be­cause you’re giv­ing away more in­for­ma­tion than nec­es­sary.

• Upvoted for truth. Hope­fully this game will avoid those pit­falls be­cause: 1) We’ve never met 2) The time it takes me to judge a rule is swamped by the time it takes me to no­tice some­body posted Also, us­ing psy­chol­ogy to get in­for­ma­tion and im­prov­ing your perfor­mance that way still re­quires ra­tio­nal­ity.

• Hu­mans are the only things ca­pa­ble of re­li­ably gen­er­at­ing things that seem non-ob­vi­ous to hu­mans. The only rea­son the uni­verse seems so good at it is be­cause we pay less at­ten­tion to the ob­vi­ous things. I don’t think we can im­prove on this is­sue eas­ily enough for it to be use­ful for the pur­poses of the game.

• Since no­body else has done it, here’s a post which I will keep ed­ited with the cur­rent Master re­quests and re­sponses:

As of 03:29 Tues­day Jan­uary 4 UTC:

``````6253  yes
21400 no
62533 yes
5142  no
60    no
6     no
6353  yes
824   no
6252  no
666   yes
6953  yes
65    no
01079 yes
``````
• Doug Or­leans told me once of a ver­sion like this he made to be played with an IRC or MUD bot (I for­get which). A rule was a reg­u­lar ex­pres­sion. (This came up when I men­tioned do­ing it with Lisp s-ex­pres­sions for the koans in­stead.)

• Rules clar­ifi­ca­tions: Mondo guesses may be changed at any time be­fore the judge­ment is posted. If some­one posts and it hasn’t been judged yet, other peo­ple can feel free to post while you wait for me to show up.

• Guess the rule here.

• I guess that you ac­cept a se­quence iff the sum of the digits in the se­quence is greater than or equal to 16.

• Cor­rect! You win the game. As a prize, you get +1 karma and it’s your turn to be Master if you want an­other game. You might want to start an­other post, this one is crowded.

• Wow, I was miles off. I thought the rule was some­thing like ‘if it is of the form 6 X 5 3...’

Also, time zones could make the mondo stages difficult; cata’s guess was at 3:32 AM for me.

• Yeah, time zones were an un­forseen difficulty. Per­haps for the next game, we could all agree on some time in ad­vance and play in a cha­t­room.

• I’ll pass on be­ing mas­ter, since I can’t re­ally be on fre­quently and re­li­ably enough to re­spond to guesses at a good pace. (I also like Nor­mal_Ano­maly’s sug­ges­tion of just or­ga­niz­ing a time to play in a cha­t­room.) If some­one else stepped up, I would play again, though. This is a fun game!

My other can­di­date rule was “if the last digit is di­visi­ble by 3,” which al­most works, ex­cept that 6 was not ac­cepted (so it would have to have a spe­cial case.)

• 0 is di­visi­ble by 3.

• Hmm, look­ing around, I guess it looks like you’re right: Most peo­ple treat zero as evenly di­visi­ble by any­thing. I didn’t know that be­fore now.

• Ini­tial strings: “6 2 5 3” is yes, “2 1 4 0 0” is no.

• Mondo, 3, I pre­dict yes is the an­swer.

• This string is no. Ben­quo gets a guess­ing point.

• eoiaslrfasjrbva

• Mondo 646

• This is yes. Cata and en­do­self get guess­ing points.

• thisonesyes

• asdfasdfnoasdfasdf

• ioqfoipvhnjoilrfhioebhreiohvr

• 0 1 0 7 9. Mondo.

• This com­ment has been up for an hour and a half and got­ten re­sponses from three of the five play­ers, with one of the other two be­ing a self-pro­claimed oc­ca­sional poster. Also I’m about to go to bed. So I’m go­ing to judge it. It is a yes. Cata gets a guess­ing point for get­ting it right.

• mkpioabdjeg

• iufveruiovvebiroabuibeiuvbeurbv

• obfuscatejudgedasyesobfuscate

• Master 6 5

Don’t add me to the turn struc­ture. I’ll post no more fre­quently then once per round, but I don’t want to hold up the game.

• Master 6 5

No.

Don’t add me to the turn struc­ture. I’ll post no more fre­quently then once per round, but I don’t want to hold up the game.

• 6 9 5 3

• [As­sum­ing Master] Yes.

• Master 666

• Re­posted for cata: Master 6 2 5 2

• 8 2 4

• 6 3 5 3

• Mondo or Master?

• Sorry, Master for both

• Master 6

• No. BTW, it is tech­ni­cally Larks’ turn. If you don’t feel like play­ing with a turn struc­ture, though, you don’t have to.

• It seems like things might flow a lot bet­ter with­out one—at the mo­ment the game (like war) has both pe­ri­ods of ex­cite­ment and pe­ri­ods of wait­ing for 8 hours, which to­gether re­quire a sub­stan­tial re-or­gani­sa­tion of one’s day.

• Yeah, given how fast this is mov­ing I’m think­ing of short­en­ing the time limit dras­ti­cally. How about the first per­son to call Mondo on some­thing sug­gests a time limit?

• I just called Mondo be­low. I would say that short­en­ing would be ap­pro­pri­ate, ex­cept that it would make it ex­tremely hard for peo­ple in differ­ent time zones to play to­gether fairly. (I’m in the US EST time zone.)

If we opted out of short­en­ing the Mondo time limit, I think we should lengthen the time limit on nor­mal guesses to be com­men­su­rate, so that peo­ple can get into a rhythm. (An en­forced de­lay on nor­mal turns might also lead to more care­ful guesses, de­signed to ob­tain bet­ter in­for­ma­tion.)

• I don’t think it should take more than 5 min­utes to come up with a valuable guess, and given that peo­ple leave their com­put­ers some­times, an en­forced de­lay would likely be an an­noy­ance. I’m in the US EST time zone too. If any­body here isn’t, let me know. I’ll judge your Mondo guess to­mor­row, un­less it gets sev­eral replies be­fore I leave.

Edit: judged it.

• I made my first guess!

Un­for­tu­nately, with the way the times worked out, there are out­stand­ing Mondo re­quests. Since I would win the game if my guess is con­firmed, I will pur­pose­fully an­swer the Mondo re­quests as if it were de­nied. Nor­mally, I as­sume that (if we were be­ing care­ful with the or­der) I would hear the re­sult of my guess be­fore other play­ers con­tinued.

• Whoops—I guess I am un­clear on the turn struc­ture, as there is not a well defined # of play­ers; but I will wait un­til Larks catches up, and yield a free turn to Larks by way of apol­ogy.

• That’s cour­te­ous of you; thanks. I was just go­ing to let peo­ple join and en­ter the turn list at what­ever point it was at when they en­tered. So far it’s just you and Larks. I’m go­ing to re­ply to his com­ment in case he doesn’t know it’s his turn.

• Master 6 0

• Master 5 1 4 2

• In case the turn struc­ture is un­clear, it is your turn. You get two turns this time, be­cause you were skipped ear­lier.

• Master 6 2 5 3 3