190.

"That's right! It's topology!" Cheng Li clapped his hands.

Then he immediately began to work on the light sand, and in a short time he smeared several editions.

In this process, Cheng Li's thinking became clearer and clearer, and the direction became clearer and clearer after several adjustments.

"Well, that's it, that's how it should be handled here...... Different areas on the map are represented by different points......"

Cheng Li kept thinking, and during the whole process, Cheng Li didn't feel that there was a flash of inspiration and countless flashes of inspiration in his mind.

However, this time, it was a matter of course, and Cheng Li naturally found the idea and method of dismantling.

The questions on the previous 2990 floors, under the influence of the inspiration of mysterious information, condensed and improved the level of engineering and mathematics, and played a magical effect at this moment.

Half an hour later......

When Cheng Li wrote down the last step of the proof and wrote down the completion of the proof, the light spot instantly reassembled the word "correct" on the screen.

Seeing the word correct on the light sand, Cheng Li's eyes couldn't help but moisten a little.

"I succeeded?"

Some of him couldn't believe it.

Although many of the questions in the previous 2990 questions are also difficult, Cheng Li knows that they are all problems that have been solved by people on the earth, and he is equivalent to just standing on the shoulders of giants, taking advantage of the convenience of knowing the answers in advance, which is equivalent to hanging up.

And this is the first time that Cheng Li has completely relied on his own ability to answer a super difficult question that no one on earth has yet answered.

The proof process written by Cheng Li is still emerging on the light sand, and the proof step of Cheng Li is divided into 21 steps, and the whole process is mainly proved by logic and topology, supplemented by a small amount of calculation, and strictly axiomatic proof.

This is compared to the method of calculating tens of billions of times by computers on Earth and forcibly solving them.

There is no doubt that the proof process that Cheng Li has now written down is more in line with the beauty of mathematics and reflects the strict and clear thinking of mathematics.

If Cheng Li published this proof process on the earth, it would definitely cause a big sensation, and it would have caused a huge sensation no less than the 1995 Fermat conjecture was proved.

But now, only the word "correct" is quietly sharing this joy with Cheng Li.

Cheng Li didn't let himself feel nostalgic for long, and in almost a dozen seconds, he completely recovered his emotions.

He looked at the time displayed in the lower right corner of the sand: "June 14, 9999 at 7:57." ”

"Time is running out, I'm stuck on this floor for a full 1 hour, I have to hurry, I hope the problems on the next 9 floors, don't be so difficult, or it'll be over. Cheng Li said with some concern.

If the last 9 layers are so difficult, and it is a question that has not been answered on the earth, then even if he can solve it in the end, I am afraid it will take a lot of time, and Qingling Island will not know if it can hold it up at that time.

After all, with every extra minute and second now, I don't know how many more people will die outside.

Cheng Li, who had this nervous consciousness, accelerated his pace and rushed directly to the 2992nd floor all the way!

"Question, please prove that there is a proposition in any formal system that contains arithmetic of natural numbers, and it can neither be proved true nor negative in this system. ”

Cheng Li breathed a sigh of relief when he saw this question.

This question is not easy, in fact, its place in the history of mathematics is crucial, and it involves the most basic discussion of mathematics.

This problem is known as Gödel's incompleteness theorem.

In fact, in the previous layers, there were some problems related to Gödel's incompleteness theorem, but none of them were proof problems of Gödel's incompleteness theorem itself.

Gödel's incompleteness theorem is the result of a certain negation, but this negation structure has brought about an epoch-making revolution in the basic research of mathematics.

Because of Gödel's incompleteness theorem, for the first time, it was clear that "true" and "provable" are two completely different concepts in mathematics.

In addition, Gödel proposed the concept of "primitive recursive function" in the process of proving the incompleteness theorem, which became the starting point of algorithm theory and provided a theoretical basis for the later development of electronic computers.

It is also reasonable for such a crucial issue to be placed on the 2992nd floor.

But in fact, the process of proving Gödel's incompleteness theorem is not too complicated, and he is more advanced in the emancipation of the mind.

Therefore, I have long known the process of proving this problem, and this question is not too difficult.

I saw that Cheng Li didn't delay for a minute or a second, and after seeing the question, he went straight forward and wrote down the answer.

"First of all, set the inner theorem and the meta theorem......

"And then here's coded with Gödel......

"Then use the immovable point theorem to prove it......

"In the end, a formula is constructed that 'says it is unprovable'. This formula is true, but it is not provable......"

"Proof is complete. ”

Cheng Li wrote a whole series of proof processes on the light sand, and finally when the proof was completed, these four words were written. The word "correct" resurfaced on the sand.

However, Cheng Li rushed out almost instantly, rushing towards the 2993rd floor.

Now he's in a race against time!

There are 8 more floors!

......

Just when Cheng Li was desperately chasing the time.

The bloody battle on Qingling Island has entered a white-hot stage.

In the sky above Qingling Island, it was almost a sea of blood at this time.

Part of it was the blood mist that exploded after countless blood demons were defeated.

The other large part is on Qingling Island, after the cultivator was killed, the blood that spilled was mixed in the blood mist, and it was even absorbed.

This is part of the reason why Blood Demon Island is so powerful in the war.

They can get stronger and stronger!

The more dead people on the battlefield, the thicker the blood mist, and the stronger the blood demons who survive and are still fighting!

And the thousands of blood-colored waterfalls are still pouring into the island protection array from the blood pool.

The field is extremely unfavorable for Qingling Island.

But!

At the heart of the battlefield, it's a little different.

At this time, the focus of the battlefield is also here.

Tuomu Zhenren, who was originally fighting with a demon king, was already grasping the head of the demon king dripping blood on his right hand in his spirit armor at this time.

And around Takumi Zhenren, there are three demon kings surrounding him, launching the fiercest onslaught!

"Haha, three demon kings, do you think you can defeat me like this?! It's too naïve, let's call you demon kings out quickly! You three are not enough to see!"

Tuomu Zhenren's entire spirit armor exudes boundless momentum, the whole person is awe-inspiring, the more he fights, the more courageous he becomes, and he even feels that he is suppressing the other three in the case of one enemy and three!

Suddenly, Tuomu Zhenren grabbed a fleeting gap, pinched his hand, and a thunderbolt slashed out.

"Nine Falls!"

This is Tuomu Zhenren's most powerful thunder method, and the thunder method already has a restraining effect on the supreme yin cultivation method like the blood demon.

After Tuomu Zhenren's spell was activated, the nine Xuan Thunder containing the aura of destruction quietly fell from the top of the heads of the three demon kings.

There are two demon kings, who sacrificed their most powerful magic weapons to resist, and barely carried it.

But there is another demon king, but because of the deliberate interference of Tuomu Zhenren, he didn't have time to sacrifice the magic weapon, and he was directly split by this Xuan Thunder!

You know, this is a demon king! It is comparable to the existence of a cultivator in the Yuan Infant Stage!

was actually cut down again by Takumu Zhenren like this!

And at this moment, there was an extremely terrifying fluctuation from the blood pool.

The blood-colored waterfall in front of him no longer falls from the pool of blood.

In the next second, a blood-colored light and shadow as high as a kilometer high unfolded from the blood pool, and then everyone saw a demonic figure of the most evil, stepping on the blood lotus in the air, and walking towards Tuomu Zhenren step by step.

All the demons on the battlefield were completely shocked by this desperate terrifying power at this moment. The battlefield that was originally fighting fiercely appeared at the same time with a slight stagnation.

The power of the demon monarch is extremely terrifying!

"You deserve my help. ”