Internet 2010

"Ding!"

When Zhang Xiaolong was thinking, an email from the Penguin Bib Team was delivered to his mailbox.

"A Cai, please accept the interface documents. In addition to the official account, you can bring a scarf assistant to WeChat this week."

After shouting on the third floor, Zhang Xiaolong returned to his office.

Now Ma Huateng is constantly mobilizing all the resources that WeChat can use, and he is not willing to delay anything.

"Where's the difference?" Zhang Xiaolong tapped the keyboard, still a little uncertain in his heart.

......

In the afternoon, Lu Zhou drove back to Yat Sen University.

Before the Spring Festival this year, Lu Ming, the invisible man of WeChat, has been planning to do a cooperation project with Yixian. The actual needs and some prototypes were naturally proposed by Lu Zhou.

Before the Spring Festival school holiday, Lu Zhou had already received a notice from Lu Ming, saying that the project school had already approved it. Naturally, WeChat provided the budget, and then Lu Ming brought some graduate students to promote the research of the project.

In this way, Lu Ming has taken root. And now that the festival is over, Lu Zhou is not so busy, so he has to take a look.

After arriving at the laboratory building of the Department of Computer Science of Yat Sen University, Lu Zhou walked to room b404 of the WeChat cooperation project.

The laboratory building Luzhou is still familiar. After all, the advertisement of Dream Valley was even working downstairs a few months ago.

When I saw the place, there was a circle of people around the door. The scene is not too familiar.

Lu Zhou, "..."

"Borrow a loan."

Lu Zhou crossed the crowd and entered, but found that no one was there. He took out his mobile phone and was about to call Lu Ming.

"Hey senior brother, where are you? Why aren't you in the laboratory?"

"Oh Luzhou. What, are you in the laboratory?"

"Yes. I'll come to see if I'm fine. I forgot to tell you in advance."

"Then wait, I'll go to the South Campus temporarily to go through some formalities. My assistant Xiaoyu is in the laboratory, and he sleeps in the innermost folding bed at noon."

Lu Zhou got up and walked to the back of the laboratory, a boy was sleeping soundly on the ground.

"..."

"And you are surrounded by people outside, don't worry about it."

"All interviews were arranged. Xiaoyu wakes up and lets him arrange it."

"Okay. That hangs."

After hanging up the phone, Lu Zhou just found a place to sit down, looking over some information on the case in his hand.

When he saw it, one of them was about sorting out the neural network, and the other one was like an exam question.

This first information is part of the theoretical form of WeChat's current data mining and text understanding system, and Lu Zhou has read the complete part earlier. And this is also some of the functions that WeChat has actually used.

For example, information classification, unstructured knowledge extraction, hot spot tracking, etc. Of course, this will also be used in some scenes of **** and violations.

In fact, Lu Zhou instructed Lu Ming to do some research related to artificial intelligence.

Of course, if you insist, Lu Zhou also feels that this AI is not as mysterious as most people think. Research on AI has been around since the dawn of computers.

Now, machine learning has also been used by many Internet companies. For example, Qiandu Tusou uses convolutional neural networks to process images, and input method products such as Sogou use recurrent neural networks to process speech recognition and text processing.

In Dream Valley, with the advancement of multiple data products, a large amount of data is being generated every day. These have also become the food for the growth of machine learning.

"Is it Senior Brother Lu?"

Lu Zhou was thinking, when he heard the voice and looked up, there were three students, and they should be the interviewers.

"Well. I am." Lu Zhou nodded.

The slightly handsome student wearing glasses said, "Hello, senior brother. I'm Zhen Zhen."

The girl beside her said, "Hello, brother, Liao Wenxiu."

"Cao Wencong."

Lu Zhou, "Hello, wait for the interview. The classmates outside the door also come in and wait."

When the students outside the door heard it, they all entered the door and sat in their seats to wait. There are not many places, and those who don't have a seat can only stand and wait.

"Brother, can you tell us about the questions you sent before?" Zhen Zhen asked.

Then she added, "Uh, if the interview is going to be involved, that's fine."

Lu Zhou picked up the test question and glanced at it, "Alright. It should be no problem to talk about it casually."

"This volume can't be described as complicated. The first is to design neurons first and turn it into a mathematical operation problem, which requires adding weights to the input data, then applying a bias to the result, and finally obtaining an activation function through an activation function. Final value. Common activation functions such as the sigmoid commonly used in biology can be used as the threshold function.

This is a simple build process. "

Lu Zhou stopped, thought for a moment, and then continued.

"Before training this network, we can use the mean square error to define the loss value to determine whether the prediction result after training meets the requirements. I won't talk about the mean square error, you should understand it."

"..."

Lu Zhou raised his eyes and glanced at the three of them, "Then the optimization of the next training will focus on reducing the loss value. Specifically, the chain derivation of the loss value function form obtained above..."

Zhen Zhen suddenly raised his hand, "Senior brother, can you do the math again?"

Lu Zhou smiled, "Which major, I didn't study mathematics well."

Liao Wenxiu, "It's not that senior brother, it's mainly the artificial intelligence direction that the graduate students did not choose, and the idea has not been opened yet."

Lu Zhou didn't say much after listening, and he had to take a pen and demonstrate to the three of them on a piece of white paper.

"In fact, loss will contain the weight w and bias parameters I just mentioned. So when we adjust w, does loss increase or decrease? This requires us to find a partial derivative of L/W.

Here we directly chain derivation, and then according to the definition of loss to find the first partial derivative, and then again according to the h value defined by the neuron ~www.wuxiaspot.com~ and then cooperate with the activation function sigmoid to finally get the total derivation Guide formula..."

Zhen Zhen, "..."

Lu Zhou, "ok, this method is generally called backpropagation. After this calculation, we can get the final change curve of the loss function when w changes. For the next problem, we can use another Stochastic Gradient Descent SGD's optimization algorithm to optimize."

Liao Wenxiu, "..."

Lu Zhou, "The main function of SGD is to adjust the weights and biases. First, we define a constant of the learning rate, which will determine the training speed of the entire neural network. In this way, we will gradually adjust the weights and biases. loss can also be continuously reduced.

Finally, the loss meets the requirements, the whole process is over, and the model comes out. "

Cao Wencong, "..."

Seeing that the three people's expressions were a little awkward, Lu Zhou felt a little embarrassed, "Uh..."

He wiped his face and directly woke up the computer next to him, "Okay, that's a bit false, I'll just write a code sample for you. I'll just use python to demonstrate, using the numpy module. Probably still According to the theoretical basis we just created, first define a few functions that need to be used..."

five minutes later.

"Okay. That's about it."

Three, "..."

This is too fast.

Zhen Zhen raised his hand again timidly, "Senior brother. Is there such a big gap between a doctorate and a graduate student? Why can't I hear it at all..."

Lu Zhou was happy when he heard it, "Don't. I'm just an undergraduate. I don't dare to make trouble in front of Senior Brother Lu."

Three people, "?!"