"Riku, did you bring today's submission?"
Yuki asked worriedly.
"Yeah, it's fine," Riku answered.
"Really? Yesterday you also said 'it's fine' but actually forgot."
Riku gave a wry smile. "This time it's really fine."
Aoi approached. "Yuki's questions have redundancy."
"Redundancy?"
"Asking the same confirmation multiple times. Information-theoretically redundant, but practical."
Yuki understood. "Because Riku has low reliability, redundant confirmation is needed."
"Harsh assessment," Riku laughed.
Aoi explained. "When channel reliability is low, the sender increases redundancy. It's a rational strategy."
"So if the other person is perfectly reliable?"
"Redundancy is unnecessary. Once is enough."
Riku opened his notebook. "But we learned before that perfect channels don't exist."
"Exactly. So in reality, moderate redundancy is always needed."
Yuki asked, "How do you determine the amount of redundancy?"
"By the channel's error rate. More errors mean more redundancy."
Aoi drew a diagram on the whiteboard.
"For example, triple redundancy systems. Send the same data three times and use majority vote to determine the correct value."
"Three times? Isn't that inefficient?"
"Efficiency drops. But reliability rises significantly. It's a tradeoff."
Riku remembered. "Come to think of it, this morning the teacher said 'tomorrow's test covers chapters 3 to 5. Repeating, chapters 3 to 5.'"
"That's also redundancy," Aoi nodded. "The more important the information, the more it's repeated."
Yuki wrote in her notebook. "Redundancy = importance?"
"Not necessarily, but there's correlation. Information where errors can't be tolerated has high redundancy."
Riku asked, "So in a love confession, repeating 'I like you, I really like you, I like you so much'?"
Aoi laughed. "Redundancy conveying emotional strength. But information content doesn't increase."
"Doesn't increase?"
"The information 'I like you' is conveyed in the first instance. Repetition only increases its certainty."
Yuki supplemented, "But the receiver feels reassured, right?"
"Exactly. There's a psychological effect. Information-theoretically redundant, but emotionally meaningful."
Aoi continued. "Actually, natural language itself is very redundant."
"Natural language is?"
"English has about 50 percent redundancy. Meaning even if half the words disappear, you can understand the general meaning."
Riku tried. "If I remove letters from 'The weather is nice today'... 'Th□ weath□r □s nic□ today'"
"You can still infer 'The weather is nice today,'" Yuki said.
"Context and grammar fill the gaps," Aoi explained. "That's natural language's robustness."
"But," Yuki asked, "can't we reduce redundancy for efficiency?"
"Like telegram style? 'Tomorrow 10 o'clock meet'"
"Yes."
"Possible. But it becomes vulnerable to noise. If it becomes 'Tomorrow □□ o'clock meet,' that's a problem."
Riku understood. "So normal conversation being slightly redundant is fine."
"Yes. Communication with margin is robust to errors."
Aoi gave another example. "In air traffic control, important information is always read back. 'Runway 34, roger, runway 34.'"
"Because lives are at stake," Yuki understood.
"Exactly. The more critical the information, the more redundancy."
Riku suddenly thought. "So Yuki confirming multiple times is kindness toward me?"
Yuki laughed embarrassedly. "More like self-defense."
"But," Aoi said, "because of those redundant confirmations, Riku's mistakes decrease. It's for both of you."
Riku became serious. "So should I also respond more redundantly?"
"For example?"
"'Brought it. Confirmed. No mistake.'"
Aoi nodded. "That's good. If the sender also adds redundancy, misunderstandings decrease further."
Yuki smiled. "From now on, let's both speak a bit redundantly."
"Efficiency might drop," Aoi added. "But reliability rises."
The three discussed the value of redundancy in the sunset club room.
Brevity is beautiful, but redundancy is kind.
Sometimes, repeated words save people.