"Aoi-senpai's explanations are really easy to understand."
Yuki said admiringly.
"Thanks. But why do you think that?"
"Um, because the examples are concrete?"
Riku interrupted. "People always say my explanations are hard to understand."
"Riku skips prerequisites," Aoi pointed out.
"Prerequisites?"
"Conversation requires common knowledge between sender and receiver. Without it, messages don't transmit correctly."
Yuki wrote in her notebook. "Common knowledge = context?"
"Yes. Information-theoretically, context provides redundancy."
"Redundancy again," Riku laughed. "Not meaning waste, right?"
"In communication, redundancy counters noise."
Aoi gave an example. "Say a sentence cuts off at 'Tomorrow,'. What comes next?"
"'Rain' or 'test'?" Yuki answered.
"Correct. From context, you can predict the next word. That's redundancy."
"But isn't that inefficient?" Riku asked.
"In a perfect channel, yes. But reality is full of noise."
Aoi drew a diagram on the whiteboard.
"Imagine talking in a cafe. It's noisy around. Even if parts of sounds aren't heard, context fills in."
"Even hearing 'To■ay ■s fu■', you understand 'Today is fun,'" Riku said.
"Yes. That's because language's statistical properties and grammar function as error correction codes."
Yuki was surprised. "Human conversation does error correction too."
"Constantly. Know the cocktail party effect? Even in noisy places, you can hear your own name."
"I've heard of that."
"The brain filters important information. Even with low signal-to-noise ratio, context reinforces it."
Riku thought. "So my explanations lack redundancy?"
"Maybe. You give conclusions abruptly without sharing prerequisites."
"Too direct."
Aoi supplemented. "Direct communication is efficient but fragile. Weak to noise."
Yuki gave an example. "Just 'Get that' doesn't tell what to get."
"But 'Get the red pen on the table' is clear."
"Redundant but certain."
"Yes. Tradeoff with robustness."
Riku asked seriously. "How can I speak more clearly?"
"First, estimate the other person's knowledge level. Next, add appropriate redundancy."
"Give concrete examples, rephrase, confirm understanding," Yuki enumerated.
"Perfect. That's human error detection and correction mechanism."
Aoi wrote on the whiteboard.
"Efficiency ←―― Optimal point ――→ Robustness"
"Adjust balance according to situation."
"Conversations with friends prioritize efficiency. First meetings prioritize redundancy," Riku understood.
"Yes. Same as communication protocols."
Yuki suddenly thought. "Emails and writing tend to be more redundant than oral, right?"
"Asynchronous communication. To prevent misunderstanding without confirmation, increase redundancy."
"Like in chat, 'OK!' 'Got it! Thank you!'" Riku gave an example.
"That's also redundancy. Reinforcing emotion and intent for reliable transmission."
"Stamps too?" Yuki said.
"Visual redundancy. Less misunderstanding than words alone."
The three laughed.
"Let's be conscious of noise-resistant conversation," Riku said.
"But not excessive," Aoi cautioned.
"Balance is important."
Outside the window, rain began falling. In a noisy world, people use redundancy as a weapon. That's the wisdom to transmit.