Criminal Psychology

"Discrete mathematics is a mathematical discipline that studies the structure of discrete quantities and their relationships. Discrete mathematics can also be said to be the basic core discipline of computer science. Discrete mathematics is also a bridge between mathematics and computer science."

These two sentences were the interpretation of Discrete Mathematics found by Lin Conggang. He read it aloud and was interrupted by the dynasty.

"I'm familiar with discrete mathematics. Why do you want Baidu, boss, look down on me!"

"So Wang Xiansen, why did Jin Xiaoan look at" Discrete Mathematics "on the bookshelf when Fu Hao mentioned" Jiang Liu "?"

"How do you know that she sees" Discrete Mathematics "! Maybe it's the book" Everything Starts with an Encounter "next to it?" Asked the dynasty.

"Because in our dormitory of Wang Shishi, I also found the same" Discrete Mathematics "belonging to Xu Haozhen ..."

"God horse?" The dynasty thundered, "unbelievable!"

"Speak well!" Xun Cong patted the teenager's head continuously.

"Fuck," Discrete Mathematics "is not advanced mathematics, it is not a compulsory university course, they are not in mathematics or computer science, why are you suddenly interested in this?"

After listening to the dynasty chattering in the ear, Lin Chen bowed his head and looked at Professor Fu, who was embarrassingly chatting with Jin Xiaoan in the screen. What they said in the conference room probably fell into Fu Hao's ear through the microphone, so Professor Fu's face now The muscles in my part are stiff, as if I don't know what to do next.

"Professor Fu ... guess, would the name of Jiang Liu be written on the title page of" Discrete Mathematics "by Jin Xiaoan?" He said to the microphone, and then it was obvious that in the picture, Fu Hao Apparently he shook because of this sentence.

But the only way to verify the guess is to do it.

This time, he didn't have trouble paying Hao anymore, but said, "Aren't you holding a document bag under your armpit, holding the cigarette case with your other hand, pretending to read the book" Everything Starts with an Encounter, "and pretending not Be careful, take out discrete mathematics. "When Fu Hao probably faced girls again, he could only play 0.1% of his usual speaking ability, so he continued to say," You can say to Jin Xiaoan: ' You read everything, I have read this reasoning novel. '"

In short, although the director's level is not high. Fortunately, Fu Hao starred from the beginning to the end, so whether it was his introduction or the next move to get the book off the shelf, it was not unexpected.

Several books fell to the ground, and Fu Hao quickly squatted down and blocked Jin Xiao'an's eyesight. He first put a reasoning book back on the table, and said in his mouth, "This book is really good. Have you finished reading it? "

Then, pretending to be inadvertent, he quickly flipped through the "Discrete Mathematics", and with the other hand still holding the cigarette case, filmed the process of reading the entire book with a very dedicated attitude.

"Is this" Discrete Mathematics "the same as Wang Shishi's?" The dynasty slowed down the screen manually, dragged the progress bar forward, and asked.

"Same." Lin Chen reached out his finger and drew a circle on the screen.

In the lower right corner of the title page of the book, the name "Jiang Liu" really appeared.

"Pay attention to the copyright information page, and then you can retreat." Lin Chen said, and then turned off the microphone.

The meeting room was quiet, Lin Chen didn't speak, and Xun Cong didn't even speak, even Captain Jiang, who was usually careless, was afraid to speak.

Therefore, the only one who dared to speak in this case was the dynasty.

"Is this a sister society, and we have to send books to each other to urge us to study hard?"

The youth's voice is light and sweet, although this question does not help much, but listening to the voice of the dynasty will make people inexplicably relaxed.

"Can you explain discrete mathematics a little?" Lin Chen asked.

"I can't explain it to you. The subject is too big and too much content, it is too difficult for you." Although the main idea of ​​this sentence is to say "your mortal IQ is too low", the dynasty's eyes are sincere and let No one had the strength to knock on his head.

When they spoke, Xun Conglian followed Fu Hao carefully after reading the original discrete mathematics, and suddenly said, "It's a bit strange."

"how?"

"Look, this book has been turned a bit old, but there are no marks on it ..." Xing Conglian pointed to the curled corner of the book and said, "Xu Haozhen gave Wang Shishi the same thing. Many times, but there are no obvious reading notes in the book. "

"What's wrong without notes? Normal people can't stand 10 pages of this kind of book?" Wang Chao said.

"Well, ask Wang Xiansen, why did you turn a book that a normal person couldn't stand reading 10 pages to rotten?" Xing Cong even hooked the dynasty's neck and asked with a smile.

At that moment, the comrade of the dynasty, Xiaoguang, appeared with three flowers together, turned to Lin Chen and said, "Achen, the boss asks you!"

Lin Chen was amused by him, and the original misty situation suddenly became suddenly bright: "The book is rotten, and it can only prove that someone has turned it many times, but can't prove anything else."

"Can't prove anything?"

"It ca n’t be proven that even Jin Xiaoan and Wang Shishi, they have read this book seriously ..." Lin Chen looked at Xun Lianlian, and said, "Most of the serious readers of professional books like this will read Take notes in the book while reading ... "

"But it's also possible that this book is precious to them, and they are reluctant to paint it!"

Seeing that the dynasty would learn from each other, Lin Chen nodded with relief, saying, "It is true, so now there are two possibilities. First, they have not read the book" Discrete Mathematics "seriously, but just put the book Turn it over and turn it over, then what exactly this subject is talking about does not really make any sense to them. Second, they have seriously studied Discrete Mathematics just because they value this book too much and have not made any notes on it ... ... which do you think is more likely? "

The dynasty scratched his head: "I don't know! But to be honest, it's not a mathematics or computer major, it's too hard to learn" discrete mathematics ", the founders of set theory are crazy ..."

"So you agree with viewpoint one?" Lin Chen interrupted the young man.

"A Chenfan, I think you are right!" Wang Chao said to him in a boneless manner, "So the answer is really that they don't understand the fart, blindly read the book?"

"Yes."

"But how do you know?"

"Oh, because you just showed me Jin Xiaoan's file, which contains her college transcript, and she linked her subjects to high school." Lin Chen said.

Upon hearing this, Comrade Wang Chaoxiao took a quick breath, and then resentfully said to him, "Achen, don't learn the boss, it's not good ..."

"Conscientiousness is very important in handling the case." Xing Cong even knocked on the dynasty and educated, "And I have nothing to show off in discrete mathematics."

"But why, are they doing any qigong, are they turning the pages and changing their meanings?" The dynasty asked, depressed.

"If you add a few other keywords in this case, such as 'Dark Network' and 'Poison', do you have any association with this?" Xing Conglian continued to ask.

Suddenly, the eyes of the dynasty changed: "Fuck, boss, I'm going to be creepy, what do you want to do in the evening!"

The young man said this, and the whole room fell into an intolerable silence.

Lin Chen clenched his right hand and fell into silence.

A rotten book, a group of college students, a controlled group, a dark webcast, a drug trade, a jewelry robbery ...

If these keywords are concatenated, it is roughly as follows: Some people have controlled a group of college students through some means, not only using them to perform various webcasts, making huge profits, but may even involve hundreds of millions of yuan in jewelry robberies and multinationals. The drug case, and the only clue they have now is that each of these students seems to have a strange copy of Discrete Mathematics.

Well, the role of this book seems to be obvious.

"What the **** is going on, I find that you don't like to explain vernacular." Jiang Chao finally couldn't help but break this kind of silent silence.

"Let's put it this way, why do the murderers behind the scenes use the dark network to broadcast live?" The dynasty asked back.

"In order not to be found!"

"Yes, whether it is the onion server or the dark network, it is essentially to protect personal services. In other words, it is an encryption method. If someone controls a large group of students, does he need to give these children Instructions, then he must also ensure that the information that he sends out has a certain degree of security, right? "

"No, don't you think that book is a password book. What age is it now, and you still play this kind of thing, and the book has not been found in the relics of other dead?" Jiang Chao responded quickly and continued: "And don't they have any dark network, so wouldn't it be more convenient to communicate on the Internet with a dark forum or something?"

"Oh, it ’s very simple. Did n’t this important thing be recovered before death? Was the criminal organization stupid? Can such an obvious clue be left for you to check? I guess Wang Shishi's book must have been for some special reason, so there is no Destroyed! And in fact, this encryption method, although very simple, is actually very useful and hidden. First of all, even roommates, few people will go through books such as Discrete Mathematics. You may find it strange to go online in the dormitory. Page is still very susceptible to suspicious. Then, group text messaging and WeChat are more likely to be tracked down, and math books, it has many formulas and many strange characters. For example, I report a number 1612, you Know if I speak 16 pages, 12 lines, or 1 page, 6 lines, 12 characters. If that word happens to be a minus sign, do you know that it means backspace, carry, or word deletion? Of course, this encryption method is theoretically possible Cracked, but this requires a lot of data and computational analysis, so the math book can really be used as an ideal password manual ... I think it is ideal because, My boss, who is his mother would take a book and work underground password link ah! "

"I'm praising me when you are." Xun Leng coldly said.

Finally, the team leader who had been hiding in the corner suddenly became interested in this topic. But rather than interest, this is in itself his most concerned question: "Do you mean, they use this" discrete mathematics "as an encryption manual for transmitting information? I think you can think of this I am afraid that this encryption method is an underground criminal organization. To be precise, it is a method that drug dealers love very much. Then I can doubt that these students are actually used secretly to deliver drugs? "

"You can doubt like this, but such doubts are basically useless now." Xun Conglian said extremely arrogantly.

"You can't stop my investigation because of your case!"

"I seem to have said that everything related to Fang Zhiming's drug factory case is temporarily out of the general direction of our investigation?"

"This is a big clue, we can follow it up!" Ren Xian suddenly raised the volume.

"Oh, did the team leader have intercepted any passwords?" Xing Conglian still looked like a salty man, but he said nothing to Ren Xian's words.

"Not for the time being, but I can review the file and maybe there will be clues ..."

"Well, if your fluke intercepted a string of passwords, and your conclusion was verified, someone manipulated a group of students to carry out countless illegal and criminal activities, including using them to sell drugs. Then, you can use this to catch the murderer behind the scenes. Or save these children? "Xing Conglian's voice was cold. He reached out and pointed at the dynasty's laptop. The picture was fixed on the slightly bowed girl in the seat." You don't understand yet, this case is similar to what we encountered before Is there any difference between those homicides? "

"I ..." Ren went on and on, apparently didn't want to understand the problem.

"What's the difference?" Jiang Chao interjected.

Lin Chen looked at the Captain of the Interpol, who was apparently popular with the two, and could not help patting the back of his hand, explaining for him: "The difference is that in ordinary murders, we only need to find the murderer, but in this case, It's not even the most important thing to find a black hand behind the scenes. "

"Isn't it important to catch the black hand behind the scenes?"

"Compared to the imminent bloodshed and a group of undergraduate students, who is behind the scenes and what he did with these students, these issues are not important, and how to solve the current problems is the most important."

After Lin Chen finished speaking, he looked at Xun Conglian again.

In fact, if he hadn't explained the sentence for himself, he would not have found out that the idea of ​​Xunlian had always been very clear, and his priorities were correct.

It was so right that he had nothing to say.

"Isn't it the fastest solution to find the killer and stop him?" Jiang Chao asked again.

"We now have two clues available, a book and a person. Suppose that the discrete mathematics is really a password table, but now we have not intercepted even the corresponding password. This clue is basically useless now, and gold Xiao'an ... You didn't pry Cheng Weiwei's mouth that day. So, when you saw Jin Xiao'an today, did you feel that you could pry open her mouth and get any useful information? "Lin Chen continued.

"Then we are still dead?" The dynasty raised his hand resentfully and asked.

"Who said it?" Xun Cong licked the ears of the dynasty, and said, "First, compare Wang Shishi's discrete mathematics with Jiang Liu's version, and then check the copyright page to find the publisher to see the print volume and Outbound records, see how many books flow to Hongjing, do I still need to teach you this kind of thing? "

"This kind of trifle is on me ..." The dynasty patted his chest, his hands were flying, "First look at the version!" He said, enlarged the previous copyright page picture, and then said: "Congratulations, sir, this book It was the first printed version in 2001 with a print volume of 5000, which means that it is really antique! "

"The good thing about the old version of the book is that it may not have been sold online anymore ..." The boy knocked down the carriage return and sighed: "bingo, I have never sold it online. I do n’t know how to evaluate you, gentleman luck."

"So, is luck good or bad?" Xing Conglian asked boringly.

"I haven't sold it online, which means that it is going through the publisher's channel. The advantage is that I can check the publisher's warehouse records. The disadvantage is that the time period is too long. It is likely that there are multiple distributors in different batches. I have ordered this book, and any system can only find the first-tier dealers, and no second-tier dealers, so ... "

The teenager snapped the epilogue.

Although many assumptions were made, after he set the search conditions, after the search, only one dealer's name appeared in the entire city of Yongchuan.

[Yongchuan Siyuan Inspirational Book Distribution Co., Ltd. Key Changwei 139xxxxxxxx]

At this time, Jiang Chao also handed over the cell phone picture to the dynasty.

The teenager took a look at the photo, quickly copied the address of the bookstore, and sent it to his boss: "The two books are the same version, the address was sent to your mobile phone, boss you can go, byebye!"

The time is 8:31 PM.

Lin Chen first looked at the time displayed on the cell phone of Xunlian, and then looked at the address. He found that the location of the dealer was exactly in the book market of Yongchuan University, so he said: "The Phoenix Book City is usually at night. It will be closed at nine o'clock, and it will open a little faster, and it should be able to catch up. "

Xing Conglian had turned around and was about to go out. When he heard his words, he suddenly turned around and said to Ren Xian: "We are nine o'clock, so the jet lag parties on the other side of the ocean probably get up and trouble the team leader to pay close attention. Anything on the Internet, just tell the kid to do it. "He said, pointing to the dynasty's head, as if not rest assured, and ordered," Don't do any communication with those people, they provide useful information , We will give money, this is the fastest. "