"What's an optimal code?"
Yuki peered into Aoi's notebook.
"A method of assigning short codes to high-frequency symbols and long codes to low-frequency symbols."
"Why?"
"To minimize average code length. Huffman coding is a representative example."
Aoi showed an example. "In English, 'e' appears most frequently. So assigning a short code to 'e' compresses the whole."
"I see," Yuki understood.
Riku suddenly said, "So can emotional expression also be optimally encoded?"
"Emotions?" Aoi showed interest.
"Short words for commonly used emotions, long words for rare emotions."
"Theoretically possible, but," Aoi thought, "human emotions aren't that simple."
Yuki gave an example. "'Like' is short."
"Because it's a frequently used emotion," Aoi nodded.
"But," Riku's face became serious, "when confessing, just 'like' doesn't feel enough."
"Why?"
"Too short, sounds casual?"
Aoi pondered. "Interesting observation. Optimal codes and emotional weight are different things."
"What do you mean?" Yuki asked.
"Information-theoretically, 'like' is an efficient code. But humans don't seek only efficiency."
"Emotions need redundancy?"
"In a sense. The more important the feeling, the more we want to convey it carefully, taking time."
Riku looked out the window. "So clumsy confessions convey feelings better?"
"It's possible," Aoi said quietly. "Roundabout expressions are inefficient but show sincerity."
Yuki understood. "Sacrificing efficiency shows seriousness."
"Costly signaling theory," Aoi supplemented. "The more costly the action, the higher the reliability."
"Like animal courtship behavior," Riku laughed.
"Humans are the same. Long letters, elaborate gifts, all costly signals."
Yuki thought. "But optimal codes also have value, right?"
"Of course. In daily conversation, efficiency is important."
Aoi showed examples. "'Good morning,' 'Thank you,' 'Sorry.' Short and frequently used."
"They're optimized," Yuki noticed.
"Over long history, language has naturally optimized."
Riku asked. "So what should I do for a confession?"
Aoi smiled. "That's for you to decide."
"But advice?"
"Balance between efficiency and emotion. Not too short, not too long."
Yuki added. "And in your own words."
"My own?"
"Riku's encoding method. Not copying others."
Aoi nodded. "Perfect advice. Individual encoding methods reflect personality."
Riku blushed. "That's difficult."
"Optimal encoding depends on purpose," Aoi said. "If the goal is minimizing average code length, Huffman coding. But if the goal is conveying emotion, different optimization is needed."
"What optimization?"
"Maximizing the probability of reaching the other person's heart."
Yuki laughed. "That can't be expressed in formulas."
"Right. That's what makes humans interesting."
Riku stood up. "Got it. I'll find my own optimal code."
"Good luck," Yuki cheered.
"But," Riku turned back, "if I fail, it's an encoding error."
Aoi and Yuki laughed.
"Communication theory assumes errors," Aoi said. "What matters is retransmission."
"How many times?"
"Until it reaches the other person."
Riku nodded. "Optimal codes and clumsy confessions. Both are my communication strategy."
The three quietly pledged to continue searching for their own optimal codes.