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Berlin, 1973

We knew that they were on to several of our people, but unfortunately we weren't sure which ones. Pulling them out before we were certain would needlessly disrupt important sources of information.

We had a pretty good guess who would be given the hit jobs; a nasty brute we'd codenamed TUNER (piano wire was known to be his "instrument" of choice).

Luckily we managed to bug his phone, and intercepted what was obviously a coded message, a monotonous synthesized voice reading off a list of paired words. Many of the words were our own code names for our people!

MUTED AARDVARK; LONG ALARM; MAGICIANS UNCLE; TRIM EEL; ABLE DINOSAUR; DESPERATE RABBIT; ETHICAL SALMON; SLIM ICE; NATURAL DRAGON; ROUND ORIOLE; PROUD BOBCAT; OPEN XIPHOID; THOROUGH HYENA; RESPONSIBLE EGRET; ELEVATED STOP

What, did they think we were idiots? Our informant MALAMUTE was targeted. We rushed him out of the city to safety.

Late that same evening we got word that a double agent, code name ORIOLE, had fallen to his death out of his fourth-floor apartment on Bunderstraße. Had we misinterpreted the message?! Or simply missed another?

Next day, a similar call came through for TUNER. Same featureless machine voice, and strangely, the exact same set of word pairs, but in a different order.

NATURAL DRAGON; TRIM EEL; OPEN XIPHOID; MUTED AARDVARK; SLIM ICE; RESPONSIBLE EGRET; THOROUGH HYENA; LONG ALARM; ABLE DINOSAUR; MAGICIANS UNCLE; DESPERATE RABBIT; ROUND ORIOLE; PROUD BOBCAT; ETHICAL SALMON; ELEVATED STOP

With so little time to work before we expected TUNER to strike, our analysts were stumped. All we could think to do was put guards on the highest-value targets that had been named.

In the morning, we learned that HYENA had been attacked by a vicious dog outside her house. She never made it to the hospital. She hadn't been on our watch list. We were losing this skirmish, badly.

The afternoon brought another phone message like the first two. We dug in, but without much hope.

SLIM ICE; MAGICIANS UNCLE; THOROUGH HYENA; TRIM EEL; OPEN XIPHOID; LONG ALARM; ELEVATED STOP; ETHICAL SALMON; MUTED AARDVARK; PROUD BOBCAT; DESPERATE RABBIT; ROUND ORIOLE; ABLE DINOSAUR; NATURAL DRAGON; RESPONSIBLE EGRET

One of the analysts -- just a kid really, named Brad --

HINT:

seemed to be reciting the lists to himself and counting on the fingers of one hand. He

jumped up suddenly and exclaimed, "They're after EEL tonight! No, wait..." He looked over his notes and added, "The indicator repeats in this one. Two of ours, then: BOBCAT as well. We've got to get them both out of the city!"

It was the best we had to go on. We rushed men to each of their locations. We were too late for EEL; he had "accidentally" dropped a radio into the bathtub with him. But we interrupted TUNER just as he was about to throw BOBCAT down a flight of stairs; our men gave chase but lost him. BOBCAT was whisked away to be debriefed. Hopefully TUNER assumed that we had just gotten lucky, but we'd have to wait for the next message to find out.

What did Brad see that we had missed in the first two phone calls? How did he know who the next targets were?

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  • $\begingroup$ Looks like a cool puzzle. I'm thinking this has to do with piano scale. $\endgroup$ – user3453281 Mar 4 '15 at 21:45
  • $\begingroup$ Very nice first question! +1. $\endgroup$ – Rand al'Thor Mar 4 '15 at 21:54
  • $\begingroup$ I am noticing something else. it says that we are setup in Berlin 1973, however this is an english puzzle ("Puzzles that crucially depend on some feature of the English language or that only work in an English formulation."). all the codewords are in english, however we are in germany. it gotta be english spies agaisnt german hitmen, so the choice of words depend on the english targets, not the german hitmen. $\endgroup$ – user3453281 Mar 5 '15 at 16:12
  • $\begingroup$ Don't read too much into the story text, @user3453281. There's no interpretation required here. The puzzle is contained solely in the lists and the knowledge of which items in the lists are marked somehow. $\endgroup$ – Josh Caswell Mar 5 '15 at 19:00
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    $\begingroup$ Piano wire - instrument of choice - But why does he not use it? $\endgroup$ – Kami Mar 19 '15 at 10:00
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The position of the target is determined by two indicators:

ELEVATED STOP and MAGICIANS UNCLE.

The number of letters in the word before the second indicator equals the distance (in word pairs) from the first indicator.

So in the first message we have ALARM before the second indicator, which means the distance from STOP to the target is 5
Same goes for the second message with distance 8
In the third message, STOP is not at the end of the message, so there are two word pairs, which have a distance of 3 (word before MAGICIANS is ICE)

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  • $\begingroup$ This is a very plausible pattern that I definitely missed when I was reviewing the puzzle. It's not the one I used to construct the lists, but in a spirit of fairness I believe that I might have to call this the winner. $\endgroup$ – Josh Caswell Mar 26 '15 at 18:38
  • $\begingroup$ @Josh, should you really mark this as the answer when it is not the intended? $\endgroup$ – Richard Li Apr 8 '15 at 21:44
  • $\begingroup$ Yes, that's the conclusion that I've worked out after some consultation, @RichardLi; it seems like the best way forward. Please feel free to answer that Meta question, though, if you have another idea. $\endgroup$ – Josh Caswell Apr 8 '15 at 21:45
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Most likely, Brad's initial procedure is

to count code names backward, starting from the last code name.

The first target is

the 6th from the last, which is ROUND ORIOLE.

The second target is

the 9th from the last, which is THOROUGH HYENA.

The third target is

the 12th from the last, which is TRIM EEL.

It's possible that Brad also identified another indicator in the messages, which is

the identity of the NEXT target. Note that the second target is already identified in the first message as the 3rd code name from the last, which is THOROUGH HYENA.

Similarly,

the third target is already identified in the second message as the 3rd code name from the last, which is PROUD BOBCAT.

However,

although the first and the second indicators match for the second target, they don't match for the third target-- indicating that either the third message was erroneously sent, or there were actually TWO targets.

To be safe, Brad decided on the later and mentioned the two possible targets.

EDIT: Brad can even use the second indicator to predict that the next target would be

ABLE DINOSAUR,

although he would need a fourth message to confirm it.

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  • $\begingroup$ A credible "false" pattern that I unfortunately missed in my review. Well-spotted. I will say, though, that Brad was not guessing; the indicator of the two targets in the last message uses exactly the same mechanism for both, and the same as that for the other messages. $\endgroup$ – Josh Caswell Mar 26 '15 at 18:35
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"The most telling feature of these lists," Brad explained at the debriefing, "was the presence of the apparently-superfluous adjective in each pair. Of course, they're necessary to form the acrostic 'MALAMUTE ADDRESS IN DROPBOX THREE{S}' from the first transmission, but that's too obvious -- it's absurd to take that as being the real message...er, sorry, sir." The agent who had made the decision to pull MALAMUTE was glaring at him.

 

"They must have been added to increase the range of some feature of the word pairs. Letter count is one such feature, but after repeated listenings of the original recording, I realized that there may also have been a reason a computer voice was used: to make a

syllable count

as clear as possible. Further analysis confirmed that hypothesis. There are two steps to the decoding.

 

"The target indicator is found first by transforming the list of words into a list of the

syllable count for each pair.

For the first list, that yields:

4, 3, 5, 2, 5, 5, 5, 2, 5, 4, 3, 4, 5, 6, 5.

 

"I squinted at this from every direction I could think of, and finally found a procedure that yielded an interesting result:

iteratively subtracting the counts, keeping the absolute value of the previous result for the next operation. So 4 minus 3 is 1, and then 1 minus 5 -- or 5 minus 1, if you prefer -- is 4; subtract 2 and get 2, and so on.

 

"This is easily done counting on your fingers, which is why you noticed me sitting at my desk muttering to myself and waggling one hand about. Start with 4 fingers,

count down 3 and you're left with 1. Each time, count down towards 0 first, then back up once you hit it. Thus, counting 5 starting with 1, hide the first finger, then count the remainder of the 5 back up,

obtaining 4."

 

Eager as he clearly was to get to the clincher, he nonetheless paused while the less-arithmetically-inclined members of the team mumbled and tried this out for themselves.

 

"Following this procedure,

the count becomes 0 at -- and only at --

ROUND ORIOLE in the first message. In the second message, the same is true of THOROUGH HYENA. In the third message, as I mentioned that day, the same indicator repeats.

The count is 0

at both TRIM EEL and PROUD BOBCAT; that's how I knew there were two targets. Er, thank you." He blushed as applause broke out.

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I think I got it.

The hint for me means that:

he was counting max to 5 and saying the words aloud, that's why I think he was counting syllables

It would fit that

Number of syllables in last word is the number of targets. Stop = 1 (Oriole), Stop = 1 (Hyena), Egret = 2 (Eel, Bobcat)

And the victims themselves are determined by:

First ANIMAL combo in row, that has same sum of syllables as the first phrase
- MUTED AARDVARK = 4 syllables => ROUND ORIOLE = 4 syllables
- NATURAL DRAGON = 5 syllables => THOROUGH HYENA = 5 syllables

the last one doesn't fit so nicely

- SLIM ICE = 2 syllables => TRIM EEL = 2 syllables but because there are two targets and nothing else has 2 syllables, we move to next animal with 3 syllables that's PROUD BOBCAT (there is LONG ALARM with 3 syllables as well, but it's not an animal)

EDIT: Thanks for the help with spoiler tags For a guy who kills with piano wire, nobody has been killed by piano wire.

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  • $\begingroup$ You've got the right starting point! But the indication of the second target in the third message uses exactly the same mechanism as the indication of the first. When you find the relevant feature for each item, those will be equal. $\endgroup$ – Josh Caswell Mar 5 '15 at 18:57
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The message was misinterpreted initially. The first message actually says to kill ORIOLE, and MALAMUTE was never targeted.

Part 1:

The key is to look for "SLIM ICE" and "MUTED". The trick with "SLIM ICE" is that the first valid target AFTER the immediate name after "SLIM ICE" is targeted. eg: "SLIM ICE" ; (SKIP) ; (target)

Explaining the second target:

Remember how I said we also have to keep an eye out for "MUTED"? In the first 2 messages, MUTED is placed before a pair of words that are NOT animals. If we are to assume that if a name isn't an animal, then it isn't an agent, it makes sense. "MUTED" is used to target the next name following the pair; eg: MUTED AARDVARK; (target) This makes it so that TUNER can see "Oh, this guy isn't an agent because it's not an animal" but if TUNER sees an animal, he can say "OK, I'm targeting this guy as well." These 2 patterns fit in with all 3 messages and targets. Essentially, the rule here is: "Check the pair of words after "MUTED AARDVARK". Is it an animal? If yes, target. If not, ignore."

But, why?

Because you can "ICE" someone (archaic slang for killing someone). Also, you SILENCE your enemies (hence MUTED).

BUT THIS DOESN'T WORK FOR THE THIRD ONE YOU LIAR!

Actually, it does because Hyena is no longer a valid target - Hyena is already dead. Thus, skip her and move over by 1.

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    $\begingroup$ But in the third message, TRIM EEL is three steps after SLIM ICE, not two! $\endgroup$ – Rand al'Thor Mar 4 '15 at 22:12
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    $\begingroup$ this seems way too arbitrary and complex. $\endgroup$ – user3453281 Mar 4 '15 at 22:15
  • $\begingroup$ I never called you a liar, and I did upvote! :-) Now I agree with you - this looks like the right answer. $\endgroup$ – Rand al'Thor Mar 4 '15 at 22:24
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    $\begingroup$ Downvoters, reasons please? $\endgroup$ – Aify Mar 4 '15 at 22:31
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    $\begingroup$ How could Brad have known that MUTED AARDVARK was a key? Your reasoning is squeezing the data a bit too hard in order to fit your hypothesis. $\endgroup$ – Josh Caswell Mar 4 '15 at 22:37

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