Hearing Lin Qi's hypothesis, the ghost frowned and started thinking, "Find a counterexample?"

Regarding this, Lin Qi could only maintain a calm expression and control himself. At the same time, he made the best of the remaining time to estimate the possibility of him breaking out of the current situation.

The cell phone which presented his best hope was still firmly held in the ghost's hands.

If he wanted to live, he had to at least send out a GPS signal.

Unfortunately, the other party had just used his voice to call Wang Ruoling and made her think nothing was wrong. Meanwhile, Lin Qi also missed the opportunity to drop a "hint" over the phone.

A spectre undead creature could exist partly as a physical body, and also completely transform into a phantom, immune to physical attacks. It was really too challenging to deal with one.

There were many unsolved mathematical conjectures, such as Goldbach's conjecture, Twin prime, Riemann hypothesis, Birch and Swinnerton‐Dyer conjecture, etc. They were all common guests among the scholarly fields. Lin Qi studied physics in his previous life and was familiar with these problems.

However, only a handful truly satisfied the criteria of being directly observable.

To be safe, Lin Qi was planning to use Goldbach's conjecture for the second round.

This competition was actually extremely unfair.

The format of the competition was proposed by the ghost. It had enough time to think about a difficult hypothesis, but Lin Qi only had a very short amount of time to think about this. He did not have enough time to come up with a truly profound hypothesis.

And the outcome of the match also depended on the opponent. Nevertheless, being able to breathe a second longer was always a good thing.

At this moment, the ghost had already started muttering calculations to itself. "Under 10, satisfied."

After a minute, it continued, "Under 100, satisfied."

In less than five minutes, the red glint in the ghost's eyes lit up again. "Under 10000, satisfied."

Lin Qi was also secretly shocked by the other party's computational ability, although some subsequent numbers would be automatically proven as they would have appeared in earlier iterations.

For example, when it came to 22, it was possible to skip the remaining 11 iterations. Also, the number 34, which would also appear during the 11 calculations, would also be naturally satisfied.

However, the fact that the other party could calculate that the numbers between 100-1000 satisfied the conjecture within such a short period of time was truly shocking. This meant that this ghost had good memory and a rapid calculation process.

For example, the average-looking number 27 would have to go through 45 steps to reach a peak of 9232, and then descend to 1 after 32 steps. The whole process was 77 steps.

This looked very much like a mage?

Lin Qi's headache intensified.

"Under 10000, satisfied."

"100,000…"

As the number increased, the ghost's calculation speed finally started to slow down.

Clearly, it was failing to find the expected "counterexample".

Mathematician Paul Erdős once said about this conjecture: "Mathematics may not be ready for such problems."

Suddenly, the ghost in front of him, "Wang Ruoling", whose face was already as pale as a sheet of paper, nearly turned transparent!

Its expression was absent-minded, muttering to itself, as if a great bell was ringing beside it.

"If the numerical sequence is written on the map, the fixed angle of the upper branch of the two digits will rotate clockwise. Otherwise, it will rotate counterclockwise. A drawing made from the number one!"

"It's actually a logarithmic spiral! It's one of the seven common features of the 32 standard spell models of necromancy!"

The ghost was in a daze.

Lin Qi did not understand the drawing in the other party's mind, but he knew about the famous logarithmic spiral which often appeared in nature. It referred to a spiral where the distances between the turnings increased in geometric progression.

In nature, the shells of parrot snails, the arrangement of chrysanthemums, the arc of eagles approaching their prey, the curve of insects approaching the light source, the structure of spider webs, and the spiral arm of the spiral galaxy were all similar to the logarithmic spiral or some form of it.

Just like the golden ratio. Nature was not a mathematician, but nature itself reflected mathematics.

Especially when it involved something as grand as a necromancy model?

At this time, "Wang Ruoling" finally began to slowly change shape. Its entire body turned into a ball of light that seemed to be invisible, like a phantom, faintly discernible.

"How did you come up with this conjecture?" The ghost's tone was cautious. It floated in the air, as if it did not dare to approach Lin Qi. It also appeared less domineering now.

Er, you are asking me? Who else can I ask?

Lin Qi could only remain silent.

"Hehe. That's right. Those complicated spell models were also the mysteries of magic that we mages discovered after accumulating our knowledge."

"Your potential is far more terrifying than I imagined."

Lin Qi blushed when he heard the praises. He had just copied the great mathematicians on earth.

He could only comfort himself by saying that he was just trying to save his own life.

Finally, after a long time, the ghost sighed.

"Before the robe came into your hands, the successor of the Phoenix clan decided to target you after reading your enrollment answer sheet. I also took the opportunity to influence his thoughts and made him hand me over to you."

"But these idiots don't know the deeper meaning of the question setter! Only the first eight questions are based on the spell models of the whole magic system! The last two questions were set by other mediocre people. Deduction and calculation questions crafted purely just to test the level of intelligence. Those who can answer them are just good at computations."

"But you, on the other hand, were able to answer the first eight questions with great acuity and leave the last two empty!

"In addition to the 'hypothesis' that you just came up with, I've already confirmed something."

The more Lin Qi listened, the more shocked he became. The praises of the other party were growing increasingly exaggerated. The ghost seemed to be overthinking things.

"Confirm what?" he asked with trepidation. At the same time, his entire body was ready to strike. He was prepared to take a risk and hide back in his memory palace.

The ghost suddenly turned to face the galaxy of stars that had been obscured by the city's development.

"I have confirmed that you have the chance to see the Door of Truth. Something that I have never seen before."

The ghost turned to look at Lin Qi. "How about a deal?"

"What deal?" Lin Qi asked warily.

"When you are in danger, I can provide you with help. I can also teach you some forbidden undead spells that have been lost over time. You will not get to learn these in the academy." The ghost offered eagerly.

"And what do you need me to do?" Lin Qi countered.

"There's no need to do anything," The ghost said respectfully, "As long as you wear me the moment you step through that door. So that I can see it for myself too."

Lin Qi lifted his chin. "You don't need to possess me anymore?"

"Compared to seeing the Door of Truth, investigating that little matter is nothing. It's just to find a way to recover my body."

"However, the reason I'm in my current state is essentially for eternal life, so that I have enough time to explore the other end of the Door of Truth. Now that I can reach my goal, albeit via a different route, there is no way I will kill the chicken just to get the egg."

Lin Qi felt it made sense, but he said, "But I don't trust you, including any methods you mention."

The ghost smiled. "I can tell you my real name and accept all of your control measures. As for the specific method, I'll tell you the reasoning behind it, and then you can find indirect ways to get Mage Mo Feng to confirm it."

Lin Qi remained unconvinced. "And then I will give you mine?"

"No need." The ghost shook his head.

Lin Qi frowned. "This is making me suspicious instead."

"No, the foundation of cooperation is based on value, not threat. I can provide you with the secrets and forbidden spells of necromancers all the way to the ninth-level. It's enough to prove my worth. Besides, even if I want it now, you won't give it to me, so why bother? When you leave, I won't have the ability to threaten you."

With that, the ghost sighed. "Student Lin Qi, remember that we mages should always think long-term."

"Fine. Then give me your real name and I'll leave here."

"Of course." The ghost smiled.

"Right, what exactly is this so-called Door of Truth?"

"The door where a mortal can become a saint. The ultimate land of magic. Those who cross it will become legendary mages."