"Hehe, it's okay, young man, can you understand?" The old man smiled, then looked at the book "Mathematical Paradoxes and Three Mathematical Crises" on the table and asked Xi Tianling.

"Well, I can understand it, but there are still some things that I can't figure out." Xi Tianling didn't expect the old man to ask this question, scratched the back of his head, and said truthfully to the old man.

"Oh? Then you basically understand everything in front of you? The old man raised his eyebrows, which also aroused his interest, and then picked up the book, pointed to the twenty or so pages that Xi Tianling had already read in front of him and asked.

"Well, I basically understand." Xi Tianling nodded and said.

The old man looked around, and there were still many people reading, so he continued to whisper to Xi Tianling. "That young man, let's go out together, how about I ask you a few questions?" ”

"Okay!" Xi Tianling could see that the old man had no ill will towards him, he should just be a little curious about his ability to understand this book, anyway, Xi Tianling was bored in the afternoon, at most he continued to soak in the library, so after thinking about it, he agreed.

Xi Tianling put the book "Mathematical Paradoxes and Three Mathematical Crises" in his hand back to its original position on the bookshelf, and then followed the old man out of the library.

As soon as he got out of the library, the old man couldn't wait to ask Xi Tianling a question: "Young man, how did you read the book you read just now?" ”

Well, "Mathematical Paradoxes and Three Mathematical Crises" introduces three paradoxes (Pythagorean paradox, Berkeley paradox, and Luo Paradox) that have had a great impact on the development of mathematics, so that readers can not only fully understand the great role of paradoxes in the development of mathematics, but also gain a clearer understanding of the ins and outs of Euclidean geometry, irrational numbers, calculus, set theory, etc. in mathematics. And it is also interspersed with anecdotes of mathematicians, integrating knowledge and fun. A good book indeed! Xi Tianling thought for a moment and then replied, although he had only read more than 20 pages, Xi Tianling could still see the general content of the content.

"Oh, I can roughly say it after only reading more than 20 pages, well, it's very good, then I'll ask you the question inside."

After that, the old man continued to ask Xi Tianling a few questions related to the content that Xi Tianling had read, and Xi Tianling answered all of them without hesitation, and some places were more appropriate than the answers in the books, when Xi Tianling answered the old man's questions more and more, the old man's eyes became brighter and brighter when he looked at Xi Tianling.

"What's your name, young man?" Finally, when he came to the school gate, the old man asked with a smile on his face.

"My name is Xi Tianling, and I haven't asked the old man for his name yet!" Xi Tianling replied politely.

"I, my name is Hao Xuewen, my family lives nearby, how about having a meal at my house, it's not too early now." After Hao Xuewen introduced himself, he couldn't wait to ask Xi Tianling, to be honest, he still has a good impression of Xi Tianling, not to mention that he is sensitive to mathematics, but he has always been polite to the old man, which can greatly increase his good impression of Xi Tianling.

"This" Xi Tianling hesitated, and before he could finish speaking, he was interrupted by Hao Xuewen next to him, "That's it, it's almost two o'clock in the afternoon now, and it just so happens that my house is also close, so let's go to my house." ”

"Okay, then bother Old Man Hao." Hearing what Hao Xuewen said, Xi Tianling hesitated for a moment and agreed, it just so happened that his stomach was already very hungry now.

Old Man Hao's home is really not far from Beijing University, almost a few hundred meters away, this seems to be a villa area, Xi Tianling didn't expect such an old man to be a local tyrant.

Follow Old Man Hao to shuttle through this villa area, the surrounding environment is really good, very suitable for the elderly to live, there are many old people around these villas, some are exercising, some are playing chess, when they see the old man Hao Xuewen next to Xi Tianling, they will nod their heads, but when they see Xi Tianling next to Old Man Hao, a trace of surprise flashed in their eyes.

"Tianling, how about arriving at my house? Not bad, right? After a while, passing through the villas and coming to the villa area, Old Man Hao stood in front of a white villa and asked Xi Tianling with a smile.

"Yes, it's quiet." Xi Tianling looked around, this villa was different from other villas, a little farther away from other villas, but the surrounding environment was indeed the best among so many villas.

"Hehe, let's go, let's go in." Hearing Xi Tianling's evaluation, Old Man Hao smiled even more, took out the key and said to Xi Tianling.

followed Old Man Hao into the villa, and the good old man shouted inside, "Old woman, today I brought someone back for dinner and cook more." ”

As soon as Old Man Hao's words fell, an old but very energetic female voice came from a place that looked like a kitchen: "Okay, you wait for a while, it's time to start eating." ”

At this time, there was a sound of rustling footsteps from the stairs next to him, Xi Tianling looked up, and the first thing he saw was a very beautiful woman, yes, very beautiful, different from the kind of youth of Cangyue, but a mature beauty.

"Grandpa, why are you only coming back now, I'm hungry." After the beauty saw Old Man Hao, a crisp and charming voice came out of the beauty's mouth.

"Hehe, isn't it a delay for a while, the meal will start soon, bear with me." Old Man Hao didn't mean to blame the woman, but gently explained to the beauty.

"Hey, who is this little brother?" The beauty did not answer Old Man Hao's words, but looked at Xi Tianling, who was sitting next to the good old man, and asked curiously.

"Oh, I forgot to introduce you, this is a young man I met in the university library, he has a high understanding of mathematics, I invited him to dinner at home when I saw it." Old Man Hao pointed to Xi Tianling next to him and introduced.

"This is my granddaughter, named Hao Yun, a tutor at Beijing University." After the good old man introduced Xi Tianling, he pointed to the beautiful woman standing next to him and introduced Xi Tianling.

Xi Tianling heard Old Man Hao's introduction, stood up, and stretched out his hand to the beauty: "Hello, my name is Xi Tianling." ”

The beauty saw Xi Tianling stretch out her hand, and also raised her slender hand like mutton fat and white jade to be with Xi Tianling: "Hao Yun." ”