"Isn't Aoi-senpai's explanation always too thorough?"
Riku said frankly.
"Too thorough?" Aoi asked back.
"Well, you rephrase the same thing and give multiple examples. Seems inefficient."
Yuki interrupted. "But isn't that why it's easy to understand?"
"Really?"
Aoi smiled. "This is redundancy, Riku."
"Redundancy?"
"In information theory, redundancy isn't 'waste.' Rather, it's 'insurance.'"
Yuki opened her notebook. "We studied this before. Noise countermeasure."
"Right. Perfectly optimized communication is fragile to noise. The slightest error collapses everything."
Aoi wrote on the whiteboard.
"Minimal code vs error-correcting code"
"Minimal code expresses information in the shortest form. But if even one bit is wrong, meaning changes."
Riku began to understand. "Error-correcting code deliberately makes it longer?"
"Correct. By adding redundancy, you can detect and correct errors."
"Concrete example?" Yuki asked.
"Parity bit. Add one bit to data, recording whether the number of 1s is even or odd."
"What does that tell you?"
"If one bit flips during transmission, parity won't match. You can detect the error."
Riku was surprised. "Just by adding one bit?"
"Yes. But you can't correct it. You don't know which bit was wrong."
"So to correct?"
"Use Hamming codes or more complex codes. Increase redundancy further."
Yuki summarized. "So to reliably deliver, you deliberately increase information."
"Perfect. That's the meaning of redundancy."
Riku suddenly thought. "Human conversation is like that too, maybe?"
"What do you mean?"
"Like, 'yeah,' 'yes,' 'understood' all mean the same thing. But sometimes you say all of them."
Aoi said happily. "Good insight. Human language is extremely redundant."
"Lots of waste?"
"Not waste. It becomes kindness."
Yuki gave an example. "'I'm fine, thank you' feels warmer than just 'I'm fine.'"
"Right. Emotional redundancy. To reliably convey to the other, you use semantically overlapping expressions."
"Using polite language excessively in emails or chats?" Riku asked.
"Safety margin through redundancy. Face-to-face is less prone to misunderstanding, so increase redundancy for certainty."
Aoi continued. "Emojis, stamps, exclamation marks. These are all redundant emotional expressions."
"Low information content, but increase certainty."
Yuki thought. "So senpai explaining thoroughly is..."
"Kindness with redundancy, maybe," Aoi was slightly embarrassed.
"Conveying the same thing with multiple expressions so the other can understand for sure."
Riku was convinced. "Not inefficient, but robust."
"Right. Same as communication theory. No perfect channel exists, so compensate with redundancy."
"Human relationships aren't perfect either," Yuki continued.
"Misunderstanding, missing things, context mismatch. Redundancy counters these noises."
Aoi summarized. "Efficiency and certainty are a tradeoff. Which to prioritize depends on the situation."
"Emergencies prioritize efficiency. But important things prioritize redundancy," Riku said.
"Perfect understanding."
Yuki smiled. "Kindness with redundancy. Nice phrase."
"Thanks. Information theory is also a textbook for human relationships."
"Maybe I'll try speaking more redundantly," Riku said.
"In moderation," Aoi laughed. "Excessive redundancy also tires the other person."
"Balance is important."
The three nodded. Redundancy was the form of kindness to reliably deliver.