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Q.E.D., vol. 15, by Katou Motohiro. Grade: B
Gurasu no Heya (Glass Room, Great Magazine, 2003). Touma has been forced to help Kana doing something that they both hate with a passion - housecleaning for the end of the old year. Kana discovers some CDs that she'd forgotten to return to her friend, Natsumi, so she uses this as an excuse to return the box and get out of chores. However, when they get to Natsumi's apartment, they find Det. Mizuhara already there. Turns out that Natsumi's grandfather - Etsurou Ooya - was just murdered, and the only people to visit his house that day were Toyoko, Natsumi's mother and the victim's daughter-in-law; Yoshikatsu Wakabayashi, the new president of the old man's company; Isao Yamauchi, the old man's friend; and the maid, Shouko Ogawa. Etsurou had retired on a huge inheritance, but he was spending all the money on vacuum tubes and hand-made amplifiers. The maid would sit in the 2nd floor foyer, knitting and listening to music on her MP3 player. The volume was loud enough to cover most of the noises coming from Etsurou's room, but quiet enough that she could hear when he yelled for her to get him tea or coffee. Toyoko would visit once a week to bring him a homemade bento lunch. He loved his late wife's cooking, and she'd taught Toyoko to cook the same way before she died. During the latest visit, Etsurou had rubbed her nose in the fact that her husband was making very little money during the recession, and that he wasn't going to give them anything himself. Yoshikatsu had received a loan to keep his company running, but he'd switched products to some weird health food and Etsurou wasn't willing to finance it any further. Isao was an old family friend who shared Etsurou's passion for making amplifiers, but couldn't afford to spend the $2,000 on one tube that Etsurou had just bought.
(The old man trying to talk to Yoshikatsu about gramophones.)
On the day, the maid remained in the foyer. Toyoko arrived with the bento, then left. Yoshikatsu dropped by to ask for another loan, then left, with Etsurou seeing him to the door. When Isao arrived, he found the body lying on the floor with a letter opener jammed in its side. A piece of looped fish line was found near the tree in the backyard, and it looks like either Toyoko had come in through the 2nd floor window and used the fish line to open and close the latch, or that Isao had stabbed Etsurou right after entering the room and then pretended to have found the body. Touma doesn't want to get involved with this crime, but Kana threatens to beat him to a pulp if he doesn't help their classmate. One common piece to the puzzle is that whenever someone talked to Etsurou, he'd interrupt them and start talking about vacuum tubes, amps, and old record players.
(Discovering the scratched record.)
So, why did Etsurou act like a jerk most of the time, and kept trying to talk about stuff no one else cared about? What was the secret behind the loop of fish line and the reason behind using the letter opener as the murder weapon? Why are all of the amplifiers he'd made numbered? Why was the record scratched, and does it hold a hidden message? Who killed him, how and when? Finally, who inherits his estate?
Lots of discussions about vacuum tubes, the advantages of analog over digital sound, and the properties of old gramophone players.
Dedekinto no Setsudan (Dedekind Cut, Great Magazine, 2003). Herbert Dawn is a math professor at MIT, and one of Touma's former teachers. He and Loki fly into Japan, and as they go through the airport, the old man asks why it's called Tokyo Airport if it's not actually in Tokyo; you could just as easily call it the LA or London airport then. Suddenly, Dawn looks like he's seen a ghost, says that John Toll must have followed them from the U.S., and he collapses briefly. They continue to Tokyo and meet up with Touma. At the moment, the boy is trying to prepare Kana for the next day's math test, and failing miserably. Herbert asks both Loki and Touma about the significance of the words "Dedekind Cut" - Loki just repeats the definition, while Touma refuses to answer. Over coffee at a restaurant, Herbert tells them about John Toll, a former TA that had been fired for deleting one of Dawn's research papers. Afterward, Toll kept returning to the research lab, and Dawn's offices, to trash the rooms, destroy an expensive vase and steal money, even after the locks were changed. Even in Japan, the hotel receives a request for room service and when the food is taken off the writing table, the letter "J" is found carved into the table top. All the old man has to go on is Touma's comment a few years ago about the Dedekind Cut.
(Kana doesn't handle math well.)
Kana is summoned to the hotel lobby, where Loki is waiting to talk to her. He explains that the Dedekind Cut was discovered by the German mathematician Richard Dedekind. It refers to two non-empty, complete sets of rational numbers. How this relates to John Toll is a mystery. At the same time, Touma has flashbacks to when he would play chess against John Toll, and the guy would talk about how it's impossible for humans to not overlook details for different problems. He'd constantly caution Touma to be aware of such "misses". At one point, he discusses the chess match between Deep Blue and Gary Kasparov. To illustrate the difference in the approaches to solving a problem for a human and a computer, John says that if a human lost a wallet on the beach, he'd just retrace his steps. The computer would use a front-end loader to dig up the entire beach. That is, humans follow patterns and patterns allow mistakes.
(Prof. Dawn discovering something on his computer, when John Toll was using it.)
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Dawn works himself up into such a frenzy that he has to be hospitalized. Touma realizes that he'd made a mistake. He visits the hospital and admits that he's the one that did everything - deleting the research paper, trashing the rooms, breaking the vase and stealing the money. Dawn smashes him in the face with his cane and orders the boy away and to never come back. Outside, Loki and Kana demand to know the meaning of this. Touma explains that Dawn is the actual criminal. The trigger event was finding Toll in his office working on their co-authored research paper and correcting the professor's mistakes. In reaction, Dawn deleted the paper and put the blame on Toll. Later, Dawn would go into a fury and swing his cane around, knocking over books and breaking the vase, but when he'd calm down he couldn't recall having done it. He also forgot about spending $200 on the vase, and thus claimed that Toll stole the cash. Touma's mistake was to refer to the Dedekind Cut to say that Dawn was being irrational, and now that's all the professor remembers. Touma had tried explaining things to Dawn several times before, but he'd keep blanking it out. In the end, Dawn happily returns to the U.S. knowing that Toll won't bother him anymore. At the airport, he asks Loki why it's called Tokyo Airport if it's not actually in Tokyo.
Obviously, we get a lot of math, both with the Dedekind Cut, and with explanations of early artificial intelligence research as it applied to writing chess programs. There's also a mention of Evariste Galois, a young French math genius who had supposedly been backstabbed by one of his professors.
Comments: I like the drawings of the vacuum tubes, but the final trick used to explain who gets the old man's inheritance is really contrived and there's no indication how Touma figures which one out of the hundreds of tubes is needed to pull it off. And I love the stuff that includes esoteric math history - I'd never heard of Dedekind or Galois before and I had to look them up on wikipedia. But, the solution to the second mystery was pretty obvious. I think it's the first time that I've seen a manga referring to Alzheimer's disease, though. Overall, recommended.