Translator: Dreamscribe
Ducky was like a shadow.
When Seo-ha opened his eyes, he would disappear.
"Stay still. Don’t come out."
Every time he whispered like this, Ducky had to hide himself in the darkness.
But Ducky did not disappear. The more he was suppressed, the sharper and more persistent he became. He kept knocking on the door without rest.
Ducky was the voice within that he had tried hard to ignore.
Ducky was an obsession.
A shackle that threatened the things he loved, the monster he had always feared.
But today, Seo-ha sought him out first.
“Ducky, let’s begin.”
With just those words, Ducky walked into the light.
Not as a suppressed impulse, but as an invited companion.
Ducky was the tenacity Seo-ha had lost and the eyes with which he analyzed the world.
Ducky emerged from the deepest part of Seo-ha’s consciousness and became one with him. And his scattered thoughts flowed together like a mighty river.
Seo-ha trembled.
A thrill of liberation that he could fully reveal his true self.
When he opened his eyes, the world had changed.
The fog that had clouded his mind lifted.
And everything appeared more vividly than before.
He picked up the book 'Theory of Computation' that he had borrowed from the library. Numbers and symbols writhed before his eyes as if they had come to life.
And his thinking accelerated.
But the clarity came with discomfort.
His brain worked like an overheated machine, spinning without rest, trying to analyze everything in sight. His breathing quickened. His nerves were stretched so tight, it felt like they might snap with just a little more strain.
But at least for today, Seo-ha decided not to care.
Seo-ha approached the blackboard and grabbed a piece of chalk. Then, in one breath, he began writing formulas.
χ(G)=min{k∈N∣∃f:V→{1,...,k},f(u)≠f(v)∀(u,v)∈E}
∀Gplanar,χ(G)≤4
“Every graph has a weakness.”
“A vertex of low degree. Five, six at most. Start breaking it from there.”
Countless shapes were built and collapsed in his mind.
When a single vertex was removed, the remaining image would find stability within four colors.
But in just one place, where five branches tangled, a crack formed. Colors overlapped and lines twisted.
His hand holding the chalk did not stop, drawing new lines.
The patterns multiplied. Exceptions piled up.
The blackboard was soon covered with graphs and figures. Seo-ha brought over a whiteboard and set it up beside him, continuing his train of thought.
Seo-ha was wandering through a forest of graphs.
No matter where he went, he couldn’t find an exit.
“Hello?”
A graph popped up before his eyes. Then they overlapped and multiplied like a monster.
As if mocking him, saying, is that all you've got?
Countless branches, countless patterns, countless exceptions.
It was an immortal being that could never die.
But all of this was a step he had expected. Seo-ha did not stop his hand.
“Don’t make me laugh. You're dying here today.”
Seo-ha’s lips twisted grotesquely.
As the night deepened, exceptions stacked up neatly on one side of the blackboard. Seo-ha brought another board and opened up a new space. Then he began converting the exceptions into a sequence of symbols and rules.
"Only the information at the boundary is encoded."
The exception figures were newly transformed.
Like condensing a vast forest into a single map, the endlessly multiplying patterns were organized into a single automata diagram.
The chalk scratched quickly, filling the board.
[State set S], [Initial state q₀], [Transition function δ]...
Then at some moment, the automaton drawn on the board closed its own circle and finalized its range.
The forest of exceptions no longer spread infinitely.
“Thirty-two.”
Seo-ha muttered low.
The countless exceptions were ultimately compressed into thirty-two patterns.
“It’s not over yet.”
This was only the bare minimum condition to solve the Four Color Theorem.
***
Click.
When the button was pressed, the sound of Gyeo-ul's performance flowed from the CD player.
Seo-ha, with a haggard face, sat in the chair.
He looked as though he might collapse at any moment, like a runner who had just finished a marathon.
His hand trembled as he lifted the water bottle.
He barely managed to replenish his fluids and took out an energy bar.
“Hoo...”
Seo-ha tilted his head back and exhaled a deep breath.
His shaking fingertips were stained with chalk dust, and his shoulders, tense with strain, felt heavy as stone.
But this was only the beginning.
The sound of Gyeo-ul’s performance gently soothed his nerves.
And gradually, his breathing began to settle.
Click.
He pulled back the blinds, and the sun was rising. Seo-ha squinted and turned his head away.
“Let’s move on to the next stage.”
The time he could use this place was limited. There was no room for rest.
Seo-ha got up from his seat.
The blackboard was crammed with figures and symbols he had built up through the night.
He looked around. There wasn’t enough space left to write.
After a moment’s thought, Seo-ha opened a box and took out A3 paper. He began taping the sheets to the wall one by one.
Soon, a massive board appeared on the wall.
Now it was time to verify the soundness of the rules he had created.
Seo-ha connected one of the compressed patterns to another. Then a flow of colors emerged, crossing through the interior and boundaries. Through the equations, Seo-ha could see with his own eyes how the four colors mixed with each other.
‘There’s no way this would go so smoothly.’
The smoothly flowing colors suddenly surged and became blocked.
Seo-ha felt as if a monster were threatening him, warning him not to come any closer.
‘No way. I just need to reinforce the rules.’
One, then another.
Before long, the wall was filled with the formulas he was drawing.
Seo-ha did not rest until every boundary fit together perfectly.
Two days passed like that.
***
On Monday morning, the warning bell for class rang.
Students in the classroom bustled about, finding their seats. But the student who was always the first to arrive was nowhere to be seen.
The one who always had his textbook open and stared straight at the board, the student who had never once been late or absent.
Everyone could feel the emptiness he left behind.
“Seo-ha isn’t here yet?”
"Did anyone see him today?"
"That's unusual. Try calling him!"
Murmurs spread among the students.
Clack.
The homeroom teacher entered the room and stood at the teacher’s desk.
His eyes briefly scanned Seo-ha’s seat.
“I received word that Seo-ha is absent due to illness today. Does anyone know anything about it?”
The students looked at one another with puzzled expressions.
“Did you hear anything?”
“Nope.”
“He looked fine on Friday though?”
A wrinkle formed between the teacher’s brows.
What he received yesterday was a single short text message.
-Teacher, I’m not feeling well, so I’ll need to be absent on Monday.
-What’s wrong? Did you go to the hospital?
A sick leave couldn’t be granted that easily.
A teacher needed to personally confirm the student’s condition or at least have a medical record.
But no reply came.
Calls went unanswered.
He had a bad feeling.
“Tae-jin and Ki-bum, go check Seo-ha’s dorm room. If he’s collapsed or anything, call me right away and let me know.”
“Yes!”
The two students got up energetically and left the classroom.
The dormitory, now empty of students, was eerily quiet.
Thump, thump!
“Seo-ha! Open the door!”
Ki-bum looked at Tae-jin. He nodded.
“Seo-ha? We’re coming in, okay?”
Beep-
When they held up the spare key they’d gotten from the dorm supervisor, the door opened.
“Huh?”
“He’s not here.”
Tae-jin looked around.
As always with Seo-ha, not a single thing in the room was out of place.
His laptop sat neatly on the desk, and all the textbooks and reference materials were in their proper spots.
A little later, they returned to the teacher’s office and reported the situation.
“He’s not there?”
The teacher raised his voice.
“Let’s check with the management center.”
The student affairs head beside him pulled out his phone and dialed a number.
“Yes, I’d like to check a student’s entry record. First year, Class 1, Yu Seo-ha.”
After a brief silence, the voice of a staff member came from the other end of the line.
“What? The Advanced Course Seminar Room?”
The student affairs director widened his eyes.
It was extremely rare for a student to use that place over the weekend.
“I’ll go check it out myself.”
The homeroom teacher jumped up from his seat.
“I’ll come with you.”
The student affairs director quickly followed him.
Yu Seo-ha was a student specially managed by the school. He wanted to confirm with his own eyes what had happened.
***
“Aigoo, my back.”
Professor Kim Ji-yoon tapped her shoulder with the hand not on the steering wheel.
Seo-ha had said he was working on some research, so she had been planning to stop by over the weekend, but an urgent schedule came up.
Now that things had finally settled down, she was planning to visit the school, even if late, before her afternoon lecture.
At that moment, her phone rang.
Ddiririring-
Ji-yoon pressed the button on her steering wheel.
“This is Kim Ji-yoon.”
-Professor, I’m sorry, but could you please come to the school right away?
At the principal’s urgent voice, sounding completely devoid of calm.
Seo-ha flashed through Ji-yoon’s mind at that moment.
“What happened? Please explain.”
-It’s Yu Seo-ha...
“What about Seo-ha?”
-It’s hard to explain over the phone. All the teachers here agreed that it would be best if you came in person... It’s the seminar room where you usually teach.
“I was on my way anyway. I’ll be there in ten minutes.”
Ji-yoon stepped on the accelerator.
Vroooom-
Before long, she arrived at the school.
Without bothering to park properly, she hurriedly got out of the car and started running.
‘What in the world happened…’
She just hoped Seo-ha was safe.
As she climbed the stairs, she saw a group of people blocking the hallway.
The principal, the vice principal, teachers, and even some students were there.
The principal spotted her and rushed over in a panic.
“Professor, please take a look at this. What on earth is Seo-ha doing right now?”
Before she could answer, he grabbed her sleeve and pulled her.
The seminar room door was wide open.
As she stepped inside, Ji-yoon nearly screamed in shock.
All three walls of the classroom were covered in paper.
Each sheet was filled with formulas and symbols, tiny figures, and graphs. To her eyes, it looked like the calculations were still in progress.
Arrows intersected in all directions, and circles, triangles, and entangled graphs collided across the walls, generating meaning.
On the massive blackboard in front, an automata diagram had been completed.
Dozens of circles were connected by arrows, and each stage was marked with different colors or symbols. It felt like the diagram was pulsing on its own, like the beating heart of a giant beast.
Only now did Ji-yoon understood the principal.
Anyone would be frightened when faced with such an overwhelming sight. None of them understood the meaning of what Seo-ha was doing. That must be why they had called her.
When Ji-yoon tried to step into the classroom, the principal raised his arm to stop her.
“No, don’t! Seo-ha is extremely sensitive right now. We’ve tried to go in several times and failed.”
Ji-yoon chuckled softly.
“It’s fine.”
‘None of the people here can understand you… but I’m not like them.’
Four Color Theorem.
As a Fields Medal candidate and the nation’s top cryptography expert, she could see through the true meaning of the massive diagram Seo-ha had created.
“Don’t come in!”
It was a sharp voice, completely unlike Seo-ha.
Ji-yoon stopped in place and looked around. The area was littered with discarded sheets of paper.
“I won’t disturb you.”
At her gentle voice, Seo-ha briefly paused the chalk that had been moving so frantically.
“I’m almost done. It won’t take long, so please wait just a little.”
How many days had he been at this?
His pale face, his trembling fingertips.
Seo-ha looked like he could collapse at any moment.
But his eyes, his eyes gleamed with such terrifying brilliance that no one dared to approach him.