"I thought I conveyed it, but it didn't get through."
Riku was dejected.
"What happened?" Yuki asked.
"I told everyone tomorrow's meeting time, but nobody came."
Aoi began analyzing. "Did you confirm transmission and reception?"
"Confirm? I just sent a message."
"That's the problem. In communication theory, ACK is needed for reliable transmission."
"ACK?"
"Acknowledgment. Reception confirmation. Confirming the other received it."
Yuki wrote in her notebook. "One-way versus two-way communication?"
"Yes. One-way, you don't know if it arrived. Two-way, you can confirm."
Aoi drew a diagram on the whiteboard.
"Transmit → Receive → ACK → Sender confirms"
"Only with this flow can you say 'it got through.'"
Riku understood. "So I should have gotten a 'I read it' reply?"
"Correct. But that alone is sometimes insufficient."
"Huh?"
"Reading doesn't guarantee understanding."
Yuki gave an example. "Even getting a 'Got it' reply, sometimes what they 'got' is unclear."
"Right. So the quality of confirmation matters."
Aoi continued. "Communication protocols have staged confirmation."
"Staged?"
"First, confirm the packet arrived. Next, confirm content is correct. Finally, confirm it was understood."
"Three stages," Yuki was surprised.
"Human conversation is the same. 'I heard,' 'I understood,' 'I acknowledged' are all different."
Riku clapped his hands. "So I need to change how I confirm!"
"Yes. Adjust confirmation depth according to importance."
"Specifically?" Yuki asked.
"For urgent matters, confirm directly by phone. For everyday things, a stamp suffices."
"You also choose the medium."
"Right. Channel selection also affects transmission probability."
Aoi summarized. "Three methods to increase transmission probability."
"First, redundancy. Repeat or use multiple expressions."
"Second, ACK. Get confirmation."
"Third, appropriate channel selection."
Riku copied into his notebook. "I see."
"Furthermore, timing is important."
"Timing?"
"Confirm the other is ready to receive. Sending when they're busy gets overlooked."
Yuki remembered. "That's why we ask 'Is now okay?'"
"Correct. A protocol confirming receiver readiness."
"Communication theory is deep," Riku was impressed.
"Human relationships are continuous protocol design."
Aoi explained from another angle. "There are also methods to reduce error rate."
"Error rate?"
"Probability of misunderstanding or transmission mistakes. To reduce this, clear expression is needed."
"Avoid ambiguous words," Yuki said.
"Right. 'Eventually,' 'probably,' 'whatever' lead to varied interpretations."
"Use specific numbers and dates."
"Perfect. 'November 25 at 10 AM' has lower error rate than 'next week.'"
Riku resolved. "From now on, I'll confirm properly."
"Good attitude. But excessive confirmation also tires the other person."
"Balance again?"
"Yes. With reliable people, minimal confirmation is fine. When uncertainty is high, increase confirmation."
Yuki summarized. "Transmission probability can be raised with effort. But one hundred percent is impossible."
"Exactly. In a noisy world, perfect communication doesn't exist."
"So don't give up, but make efforts to raise the probability."
Aoi smiled. "That's the teaching of information theory."
The three nodded. Increasing transmission probability. That was the essence of communication.