Criminal Psychology

"Discrete mathematics is a mathematical discipline that studies the structure of discrete quantities and their interrelationships. 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 are the explanation of "Discrete Mathematics" that Xing Conglian just found. He read it aloud, and then was interrupted by the dynasty.

"I am familiar with discrete mathematics, boss, why do you still need Baidu, do you look down on me!"

"Then, Wang Xiansen, why did Jin Xiaoan glance at "Discrete Mathematics" on the bookshelf when Fu Hao mentioned "Jiangliu"?"

"How do you know that she is reading "Discrete Mathematics"! Or maybe it's "Everything Begins When We Meet" next to it?" Wang Chao asked.

"Because we also found the same "Discrete Mathematics" belonging to Xu Haozhen in Wang Shishi's dormitory..."

"Wonderful horse?" Dynasty shuddered, "Unbelievable!"

"Speak well!" Xing Cong patted the boy on the head repeatedly.

"Damn, "Discrete Mathematics" is not advanced mathematics, it is not a compulsory course in universities, and they are not from the Department of Mathematics or Computer Science, right? Why are you suddenly interested in this?"

Hearing Wang Chao chattering in his ears, Lin Chen lowered his head and looked at Professor Fu who was chatting awkwardly with Jin Xiaoan on the screen. Most of what they said in the conference room fell into Fu Hao's ears through the microphone, so Professor Fu's face His muscles were stiff, as if he didn't know what to do next.

"Professor Fu... Do you guess that Jiang Liu's name is written on the title page of Jin Xiaoan's book Discrete Mathematics?" He said this into the microphone, and then it was obvious that Fu Hao Obviously shaking at his words.

However, the only way to verify the guess is to do it.

This time, he didn't make things difficult for Hao Fu anymore, but said: "Don't you have a file bag under your armpit, hold a cigarette case with the other hand, pretend to read that "Everything Begins with Encounter", and then pretend not to Be careful, take the discrete math out." Fu Hao probably could only use [-]% of his usual speaking ability when facing girls again, so he continued to ask, "You can say to Jin Xiaoan:' You read everything too, I have read this mystery novel too.’”

In short, although the director's level is not high.But fortunately, Fu Hao acted in his embarrassing nature from beginning to end, so whether it was his quotation or the next action of taking the book off the shelf, it was surprisingly not abrupt.

Several books fell on the floor, Fu Hao quickly squatted down to block Jin Xiaoan's sight, he first put a reasoning book back on the table, and muttered: "This book is really good, have you finished it yet? "

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

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

"Same." Lin Chen stretched out his finger and lightly 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 take a picture of the copyright information page, and then you can retreat." After Lin Chen finished speaking, he turned off the microphone.

The meeting room fell silent, Lin Chen didn't speak, Xing Conglian didn't speak, even Captain Jiang, who was usually careless, didn't dare to speak.

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

"Is this a sorority, and you still have to send books to each other to urge you to study hard?"

The young man's voice was soft and sweet. Although this question didn't help much, just listening to Dynasty's voice made people feel at ease inexplicably.

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

"I can't explain it to you. The subject is too big and the content is too much. It's too difficult for you." Although the general meaning of this sentence is to say "you mortals have too low IQ", Wang Chao's eyes are sincere and let People don't even have the strength to knock him on the head.

While they were talking, Xing Conglian followed Fu Hao to read the original Discrete Mathematics seriously, and suddenly said, "It's a bit strange."

"how?"

"Look, this book is a bit old, but there is no mark on it..." Xing Conglian pointed to the corner of the curled book, and said, "The book that Xu Haozhen gave to Wang Shishi is also in the same situation. Been there many times, but there aren't any obvious reading notes in the book."

"What's the matter with no notes, normal people can't stand this kind of book after reading 10 pages?" Wang Chao asked.

"Then, Wang Xiansen, why did you turn to pieces a book that normal people can't bear to read even 10 pages?" Xing Conglian hooked Wang Chao's neck and asked with a smile.

At that moment, Comrade Wang Chao had a flash of inspiration and turned to Lin Chen and said, "Ah Chen, the boss is asking you!"

Lin Chen was amused by him, and the original foggy situation suddenly became clear: "The fact that the book has been flipped through can only prove that someone has flipped through it many times, and it cannot prove anything else."

"Can't prove what?"

"I can't prove that whether it's Jin Xiaoan or Wang Shishi, they have read this book seriously..." Lin Chen glanced at Xing Conglian, and said, "Most people who read professional books like this seriously will know how to read this book." Reading and taking notes in the book..."

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

Seeing that Wang Chao would draw inferences from one instance, Lin Chen nodded with satisfaction, and said, "That is indeed the case, so now there are two possibilities. After reading and flipping, then what this subject is about actually has no meaning to them. Second, they have studied "Discrete Mathematics" seriously because they cherish this book too much and have not made any notes on it... ...which do you think is more likely?"

Wang Chao scratched his head: "I don't know! But to be honest, I'm not a mathematics or computer major. Learning "Discrete Mathematics" is too difficult, and the founders of set theory are crazy..."

"So you agree with point one?" Lin Chen interrupted the boy.

"A Chenfan, I think everything you say is right!" Wang Chao said to him very spinelessly, "So the answer is really that they don't understand farts, so they flipped through the books?"

"Yes."

"But how do you know?"

"Oh, because you showed me Jin Xiaoan's file just now, and there is her college transcript in it, and she failed in high mathematics." Lin Chen said.

Hearing this, Little Comrade Chao Chao took a quick breath, and then said to him sadly: "Ah Chen, don't imitate the boss, it's not good..."

"Conscientiousness is very important in the process of handling a case." Xing Conglian knocked on the Dynasty and taught, "And there is nothing to show off if you have learned discrete mathematics."

"But why, are they practicing some kind of qigong? Turning the pages of the book can reveal its meaning?" Wang Chao asked depressingly.

"If you add several other keywords in this case, such as 'dark web' and 'drugs', do you have any associations with this?" Xing Conglian continued to ask.

In an instant, Wang Chao's eyes changed: "Damn, boss, I'm going to be creepy, what's wrong with you thinking about it at night!"

After the young man said this, the whole room fell into an unbearable silence.

Lin Chen clenched his right hand, and also fell silent.

A torn book, a group of college students, a controlled group, a dark webcast, a drug deal, a jewelry robbery...

If these key words are connected in series, it is roughly like this: someone has controlled a group of college students through certain means, not only using them to conduct various webcasts and making huge profits, but may even involve hundreds of millions of dollars in jewelry robberies and transnational crimes. Drug case, and the only clue they have now is that each of these students seems to have a strange "Discrete Mathematics" in their hands.

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

"What's going on, I found that you don't like to explain plain words." Jiang Chao finally couldn't help breaking the silence that was too tacit.

"Let's put it this way, why did the murderer behind the scenes use the dark network to broadcast live?" Wang Chao asked.

"In order not to be found out!"

"Yes, whether it is the onion server or the dark web, they are essentially services for protecting personal privacy. 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 also has to ensure that the information he sends out is safe, right??"

"No way, do you think that book is a password book, what age is it now, and you still play with this kind of thing, and you haven't found this book in the relics of other deceased?" Jiang Chao reacted quickly and continued: "And don't they have a dark network, so wouldn't it be more convenient to have a dark forum or something to communicate on the Internet?"

"Oh, it's very simple. Don't organizations take back such important things before they die? Are criminal organizations stupid? Can you keep such obvious clues for you to investigate? It is estimated that Wang Shishi's book must be due to some special reasons, so there is no Destroyed! In fact, although this encryption method is very simple, it is actually quite effective and concealed. First of all, even if you are a roommate, few people will read a book like "Discrete Mathematics". It is quite easy to attract suspicion. Then, it is easier to be traced when sending text messages and WeChat in groups. As for mathematics books, there are many formulas and strange characters. For example, if I report a number 1612, you Do you know if I mean 16 pages and 12 lines, or 1 page with 6 lines and 12 words? If that word happens to be a minus sign, do you know that means backspace, carry or delete? Of course, in theory, this encryption method can It can be cracked, but it requires a lot of data and calculation analysis. Therefore, Mathematics Book Bar can really be regarded as an ideal password manual... The reason why I think it is ideal is because, except my boss, who the hell It will link a good book with underground cipher work!"

"I thought you were praising me." Xing Conglian said coldly.

Finally, Team Leader Ren, who had been hiding in a corner, suddenly became interested in this topic.But it's not so much an interest, it's better to say that this is what he is most concerned about: "You mean, they use this "Discrete Mathematics" as an encrypted manual for transmitting information? I think the reason why you can think of this , I’m afraid it’s because this encryption method is used by underground criminal organizations, to be precise, it’s a method that drug dealers love to use, so I can doubt that these students are actually secretly used to deliver drugs?”

"You can doubt like this, but such doubt is basically useless now." Xing Conglian said very coldly.

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

"I seem to have said that everything related to Fang Zhiming's drug factory case is not within the general direction of our investigation?"

"This is an important clue, we can follow along!" Ren Xian suddenly turned up the volume.

"Oh, did the team leader ever intercept any passwords?" Xing Conglian still had a nonchalant expression, but his words made Ren Xian speechless.

"Not yet, but I can review the files, maybe there will be clues..."

"Okay, if you are lucky enough to intercept a string of passwords, and then your conclusion is verified, that is, someone manipulated a group of students to carry out countless illegal and criminal activities, including using them to sell drugs, and then, you can use this to catch the murderer behind the scenes or save Are these children?" Xing Conglian's voice was very cold, he reached out and pointed at Dynasty's laptop, and the picture was fixed on the girl who lowered her head slightly in the seat, "You still don't understand, this case and those we encountered before Does homicide make any difference?"

"I..." Ren Xian hesitated to speak, obviously he didn't want to understand this question.

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

Lin Chen looked at the captain of the criminal police who was obviously angry with the two, couldn't help but patted the back of his hand, and explained for him: "The difference is that in ordinary homicide cases, we just need to find the murderer, but in this case, Even finding the mastermind behind the scenes is not the number one priority."

"Isn't it important to catch the mastermind?"

"Compared with the imminent bloodshed and a group of college students being manipulated, who is behind the scenes and what he did with these students is not important. How to solve the current problem is the most important."

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

In fact, if Xing Conglian hadn't explained it himself, he wouldn't have discovered that Xing Conglian's thinking had always been very clear, and his judgment of which should come first and which should come first could not be more correct.

It was so correct that he had nothing to say.

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

"We now have two usable clues, a book and a person. Assuming that the discrete mathematics book is really a password table, but we have not intercepted even a corresponding password, this clue is basically useless now, and Jin Xiaoan...you didn't pry Cheng Weiwei's mouth that day, so, seeing Jin Xiaoan today, do you think you can pry her mouth open and get any useful information?" Lin Chen continued.

"Then we are still at a dead end now?" Wang Chao raised his hand sadly and asked.

"Who said that?" Xing Conglian picked Wang Chao's ear and said, "First compare Wang Shishi's Discrete Mathematics book and Jiang Liu's to see if it is the same edition, and then check the copyright page to find the publishing house to see the print volume and Check out the library to see how many books have flowed to Hongjing, do you need me to teach you about this kind of thing?"

"This kind of trivial matter is on me..." Wang Chao patted his chest, his hands flying like flying, "Look at the version first!" He said, zooming in on the picture on the previous copyright page, and then said: "Congratulations, sir, this book It was the first printed version in 2001, with a print run of 5000, which means it is really an antique!"

"The advantage of the old version of the book is that it may not have been sold online again..." The young man hit enter and sighed: "Bingo, I really haven't sold it online, sir, I don't know how to evaluate you luck."

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

"It has not been sold online, which means that it is through the channel of the publishing house. The advantage is that I can check the release records of the publishing house. The disadvantage is that the time period is too long, and it is likely that there are many distributors in different batches. I ordered this book, and any system can only find first-tier dealers, not second-tier dealers, so..."

The young man abruptly cut back on the ending.

Although he made a lot of assumptions, after he set the search criteria and the search was over, only one dealer's name appeared in the entire Yongchuan City.

[Yongchuan City Siyuan Inspirational Book Distribution Co., Ltd. Key Chang Wei 139XXXXXXXX]

At this time, Jiang Chao also handed over the mobile phone pictures to Dynasty.

The teenager glanced 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 has been sent to your mobile phone, boss, you can go, byebye!"

The time is 8:31 in the evening.

Lin Chen first looked at the time displayed on Xing Conglian's mobile phone, and then looked at the address. He found that the location of the dealer happened to be in the book market of Yongchuan University, so he said: "Phoenix Book City is usually at night. It will close at nine o'clock, so if you drive a little faster, you should be able to catch up."

Xing Conglian had already turned around and was about to go out. Hearing his words, he turned around abruptly and said to Ren Xian: "We are at nine o'clock, so the jet-lagged party on the other side of the ocean will probably wake up soon. Please, Team Leader Ren, keep an eye on it. If you have anything to do online, just ask this kid to handle it.” After he finished speaking, he pointed to Chao Chao’s head, as if worried, and then ordered, “Don’t communicate with those people, they provide useful information , we will give the money, which is the fastest."