"If you had to describe Aoi-senpai and Yuki's relationship in one word?"
Riku suddenly asked.
Yuki pondered. "That's difficult."
"That's an encoding problem," Aoi said.
"Encoding?"
"Representing complex information with limited symbols. Human relationships can also be encoded."
Riku opened his notebook. "How?"
"For example, the word 'friends.' This is a code that compresses various relationships."
Yuki understood. "But 'friends' alone doesn't tell the specific nature of the relationship."
"Exactly. So sometimes more precise encoding is needed."
Aoi drew a diagram on the whiteboard.
"There's a method to represent relationships in multiple dimensions. Trust level, intimacy level, shared time, etc."
"Like a vector," Riku said.
"Exactly. Relationship = (trust: 0.9, intimacy: 0.7, shared time: 300 hours). A multidimensional vector."
Yuki became interested. "Then we can express it accurately."
"We can. But there's a problem."
"Problem?"
"Too much information. When explaining to someone, conveying all dimensions is inefficient."
Riku laughed. "So that's why we compress to 'friends.'"
"Yes. In information theory, this is called lossy compression. Some information is lost, but it becomes efficient."
Yuki wrote in the notebook. "What's the difference between lossless and lossy compression?"
"Lossless compression can be fully restored. Lossy compression keeps only important features."
"Specific example?"
Aoi explained. "Think of photos. PNG is lossless, JPEG is lossy. JPEG discards fine details, but it's sufficient for human eyes."
"Complete reproduction isn't needed for relationships either?"
"In most cases, no. 'Senior and junior,' 'friends,' 'colleagues.' These are rough classifications, but sufficient for daily conversation."
Riku asked, "But sometimes you want to convey precisely?"
"Then you increase the bits. 'Close friend,' 'trustworthy senior,' 'comfortable person to be with.' More bits for more accuracy."
Yuki understood. "Change encoding precision according to purpose?"
"Exactly. Adaptive encoding. Choose optimal representation according to context."
Aoi gave another example. "Same with emotions. 'Happy' is a rough code. But 'a happiness that warms the heart' is more detailed."
"More detail is better?"
"Not necessarily. You need to consider the receiver's processing capacity—channel capacity."
Riku looked confused. "Channel capacity?"
"The limit of information the other person can understand. Overly complex explanations don't get through."
Yuki gave an example. "When meeting someone for the first time, they can't remember a detailed self-introduction."
"Exactly. So initially use coarse encoding. Gradually refine it."
Riku laughed. "Is the process of becoming friends a process of increasing encoding precision?"
Aoi looked impressed. "Good insight. The deeper mutual understanding grows, the more compressed communication becomes possible."
"Compressed communication?"
"When shared knowledge increases, you can convey much with few words. 'That time' becomes understood."
Yuki nodded. "Information-theoretically, mutual information is increasing."
"Exactly. As common context increases, efficient encoding becomes possible."
Riku wrote in his notebook. "So what's perfect encoding?"
"Perfection doesn't exist," Aoi answered. "There's always a tradeoff. Precision and efficiency, brevity and accuracy."
"Balance is important?"
"Yes. Like Huffman coding—encode frequent things briefly, rare things at length."
Yuki asked, "What's frequent in human relationships?"
"'Good morning,' 'thank you,' 'sorry.' These are short and frequently used."
"Efficient codes," Riku understood.
Aoi smiled. "Language itself is a code system optimized through long evolution."
"So," Yuki asked, "how would you encode your relationship with me now?"
Aoi thought briefly. "'Companions learning together,' maybe. But that's just one encoding."
"There are other encodings?"
"Many. Encoding changes with perspective. That's the richness of human relationships."
The three discussed relationship encoding in the sunset club room.
Perfect expression doesn't exist, but appropriate encoding is possible.
And that encoding itself becomes dialogue that deepens relationships.