kscans

Chapter 8 - Chapter 6: Part One - How to Utilize an Expert

"Monster Floods do not occur in the west."

The old man had been watching over Alfina as she earnestly explained. But the words he spoke after turning to face me were utterly dismissive. Where had the kindly old gentleman stroking his long white beard gone?

Three days after our hypothesis review session in the archives, I, Mia, and Alfina were in the head librarian's office. Across from us sat the old man himself, the master of the room. He was around seventy. His career was apparently an exceptional one, considering he was the fourth son of a baron.

However, given his achievement of devising a method to predict Monster Floods, his current post was laughably unimportant. I wanted to curse my past self for ever feeling sorry for him.

From what I'd researched over the last three days, I thought he was an interesting character, but it seemed he was less than pleased by the commoner boy standing next to the princess. Incidentally, there were two commoners in the room, but Mia was the one offered tea and sweets.

The moment Alfina first introduced me as her friend, his attitude hardened instantly. Is this a "bad influence on his cute granddaughter" sort of thing? I was just as surprised to be called her friend, so I wish he’d cut me some slack. But if I tried to explain our relationship any other way, I’d probably be labeled an agitator or a villain whispering in the sovereign's ear.

In fact, he's probably already slapped those labels on me in his head.

Right, no need to glare. You don't have to worry. I know full well that we live in different worlds. For starters, I hold no admiration or anything of the sort for the world she lives in. She’s definitely a beautiful girl who’d make anyone fall for her at first sight, if she weren't a walking landmine of a princess. This whole situation is just a product of coincidence. If anything, this happened because I tried my best to keep my distance.

As I came up with excuses I couldn't say aloud, I struggled to force my sullen expression into a serene, Buddha-like smile. By the way, there's a saying that "even the Buddha's face will get angry if struck three times," but in this world, if a commoner "angers" a noble three times, they have a high probability of becoming a buddha for real.

"Considering the circumstances, the highest probability is a Monster Flood. That is why we would be most grateful for your wisdom, Head Librarian..."

"One can invent any number of armchair theories. Assuming a catastrophe does occur, what do you believe is the probability that it will be a Monster Flood?" he asked, propping his chin on his hand with a look of annoyance as I added my piece.

"Well, I'd say we'd be lucky if it's three in ten."

"What!?" "..."

The one who cried out was Alfina. I couldn't blame her. A highest probability of less than a third sounded far too unreliable. But that’s just how it was. I looked straight at Fulsy. The old man's choice of words, contrary to his attitude, showed that he was someone I could reason with on my own terms.

"And what is the reason for considering such a flimsy hypothesis?"

"As I said before, it is still the greatest possibility. And Monster Floods are preventable, which means the underlying mechanism is understood to some extent. In other words, this hypothesis is verifiable."

"To some extent, you say."

"T-To put it another way, if we borrow your wisdom, we can turn this hypothesis into a certainty of one hundred percent or zero. If we determine a Monster Flood will occur, wonderful. If not, we can move on to the next hypothesis."

I answered without averting my gaze.

"So that's why you came here. I see, I see..."

Fulsy finally lifted his chin. He grinned, one eye crinkling.

"I heard from the princess that she wished to borrow my wisdom. But you, you don't need my wisdom, or my judgment. You're just telling me to hand over my knowledge. That's what you're really saying, isn't it?"

"That's not true. Ricardo-kun is..."

"Correct. That is how you utilize an expert."

"Ricardo-kun!? W-Wait, I must explain..."

Alfina looked aghast. Fulsy glared at me, then silently rose from his seat. Alfina shifted as if to stop him.

"The mountain ranges, which are magic veins, and the surrounding Rubel Wald are the domain of monsters. Normally, the beasts do not leave those areas. A Monster Flood is when monsters suddenly form packs and attack the flatlands, that is, human territory. You must have learned in history that a large-scale Monster Flood originating from the eastern Rubel Wald two hundred years ago is said to have caused the fall of the old dynasty, yes?"

The old scholar stopped in front of a stone slate set into the wall and suddenly began a lecture. Beside it was a map depicting the entire kingdom, with many marks on the eastern mountain range.

"Nothing on that scale has occurred since, but even now, the east experiences small-scale Monster Floods once every six years on average, and medium-scale ones once every ten years. And the cause..."

Fulsy pointed to the eastern mountain range.

"Is fluctuations in the magic veins. The miasma that constitutes half of a monster's energy, in other words, disordered magical power, wells up from the depths of the earth. Therefore, the structure of the mountain range itself can be seen as the flow of magic. As you can see, the eastern range is intricately complex."

Several red lines were drawn on the eastern mountains, with circles where they intersected. I see. So I should think of the mountains as rivers through which magic flows.

"As a result, there are calm periods when the flows of magic cancel each other out, and turbulent periods when they overlap and intensify. This affects the ecosystem of the monsters, which are dependent on magic. To put it simply, when magic increases, so do the monsters. If the magic then decreases, the monsters starve. The result is a Monster Flood."

Ordinary living things, including humans, live on energy from the sun. But monsters survive by taking in not only that, but also the magic that wells up from the earth. On my Earth, too, there were ecosystems that didn't depend on sunlight, instead drawing energy from deep-sea hydrothermal vents.

"On the other hand, the western mountain range is simple. Large fluctuations in magic like those in the east cannot occur. This is what you all wanted to know, isn't it?"

Now what will you do? Fulsy seemed to ask me with his eyes. He had a point. The western range was comparable in size to the eastern one, but it extended in a straight line from south to north. His explanation was logical. Given that the catastrophe was prophesied for the west, the probability of it being a Monster Flood was not high.

I had to abandon my attachment to my own idea and judge it by the same standards I'd used to rule out floods and volcanic eruptions.

Alfina gave me a troubled look. I had said I would retract the hypothesis if the probability was revised, and I meant it. But...

"May I borrow the slate? Mia, please explain that data."

Mia and I hadn't been wasting our time these past three days, either. Mia moved to stand before the slate, as if swapping places with Fulsy.

"The kingdom's weather is stable, and the temperature is nearly the same in the east and west. The only significant difference is in rainfall, and the harvest yield corresponds well with the amount of rainfall. The correlation coefficient is 0.86."

Mia began her explanation. Fulsy tilted his head, wondering what was happening. Alfina, too, was confused by this development, which wasn't part of our plan.

"Correlation coefficient?"

"To put it simply, it's a numerical value that quantifies the strength of the relationship between two variables. The relationship between harvest yield and sales of luxury goods, for example. It is represented by a simple calculation like this."

Mia wrote the formula on the slate.

"An interesting method of calculation. It is quite logical. But can the harvest yields themselves be trusted? No matter how brilliantly you calculate with incorrect data, you will only amplify the error."

Harvest yields were closely tied to taxes. In other words, the nobles tried to fudge the numbers. Fulsy's words, by the way, were quite risky. Tax evasion among the nobility was a rampant, open secret that no one dared speak of. Mia glanced at me, asking for permission to press forward. I nodded.

"We cannot trust the data from the noble domains. However, the harvest yields from the crown lands, which are managed by officials partly to keep the nobles in check, are trustworthy to some extent. This is also clear from the variance in the yields."

Mia affixed a piece of paper to the slate, on which the harvest yields from noble and crown lands were plotted as dots. It was as good as saying that the harvest from noble domains didn't show a normal distribution, that it was skewed by some factor... or rather, by someone's convenience.

"The variance in the harvest yields from the noble domains is unnatural. The crown lands, on the other hand, are closer to what one would expect naturally. The results are shown by this formula, and there is a clear difference. For our data, we have used the yields from the crown lands."

This data was a bombshell. It could lead to more efficient investigations of tax evasion by the nobility. But for now, my priority was to capture this old man's interest. I had to trust my intuition that he was someone I could talk to in numbers.

"Interesting. To express the difference from the mean, you multiply them and then... no, wait. This is the mathematization of the concept of expected randomness..."

As I'd hoped, Fulsy was completely absorbed in the calculation.

"Returning to the main topic. When we divide the data between east and west, the western end has a correlation coefficient of 0.9, meaning the harvest yield and rainfall almost perfectly match. In contrast, the eastern end drops to 0.7. The reason is the existence of years with 'bumper crops' that don't match the rainfall data. The most recent were in the Kingdom Calendar years of 324, 314, and 309. In these years, the harvest yield was 'higher' than predicted by the rainfall."

Fulsy put a hand to his beard.

"Those are the years when Monster Floods occurred in the east."

"According to Princess Alfina's prophecy, the west will have a bumper crop this year. The east, however, will not. In other words, it is not only the prophecy of catastrophe that is strange, but the prophecy of a bountiful harvest as well."

Mia’s words surprised them both. We had been surprised too when we discovered it. To think there was a connection between the disaster of a Monster Flood and a bumper crop. So much for my talk about the importance of primary sources. It had been a complete blind spot.

Now, it was my turn. I stood up and pointed at the map.