"Haven't those two been awkward lately?"
Riku pointed toward the hallway.
"You noticed," Aoi said quietly. "Their channel is becoming unstable."
"Channel?" Yuki asked back.
"Relationships between people can also be viewed as channels. Sending, receiving, and understanding messages."
"I see," Yuki understood. "And unstable means?"
"Noise increases, capacity decreases, mutual information declines."
Riku sat down. "Mutual information?"
Aoi wrote a formula in the notebook. "I(X;Y) = H(X) - H(X|Y). Information about X obtained by knowing Y."
"That's difficult," Riku held his head.
"Simply put, how much the other person's state relates to your own state."
Yuki asked for an example. "Specifically?"
"A couple who understand each other perfectly has high mutual information. One's feelings strongly predict the other's feelings."
"Conversely, when they're awkward?"
"Mutual information is low. Can't read the other's feelings. Messages don't get through."
Riku thought. "So how can it become stable?"
"Improve the channel quality. Reduce noise, expand bandwidth."
"Reduce noise?" Yuki asked.
"Reduce misunderstandings and assumptions. Clear communication."
Aoi continued. "Expanding bandwidth means increasing the frequency and variety of communication."
"Increasing the number of conversations, using methods beyond words."
"Yes. Multi-channel communication."
Riku stood up. "Should I say something to them?"
"Intervening could also be noise," Aoi said carefully. "They need to repair the channel themselves."
"But it's hard just watching."
"I understand the feeling. But they own the channel."
Yuki offered another perspective. "Maybe the channel temporarily disconnecting is also necessary."
"What do you mean?" Riku asked.
"For a reset. When too much noise accumulates, disconnect once and rebuild."
Aoi nodded. "Like protocol renegotiation."
"Reevaluating the relationship?"
"Yes. When the old channel stops functioning, establish a new channel."
Riku pondered. "Can that lead to a better relationship?"
"It's possible. But there's no guarantee."
Aoi said quietly. "Communication theory, like human relationships, is probabilistic. Even with best efforts, failure can occur."
"Then what should we do?"
"Remember Shannon's channel coding theorem. Below channel capacity, communication is possible with arbitrarily small error rate."
"Meaning?"
"Understand the capacity of your channel. Don't try to forcibly send information exceeding capacity."
Yuki understood. "Don't expect too much or demand too much."
"Yes. Accept the channel's limits."
Riku looked out the window. "What's the capacity of those two's channel?"
"I don't know. But they need to find it."
Aoi supplemented. "And within that capacity, find the most efficient encoding."
"Devising how to say things, choosing timing."
"Exactly. Communication is a process of encoding and decoding."
Yuki said quietly. "Do you think our channel among the three of us is stable?"
Aoi smiled. "Relatively stable. But maintenance is necessary."
"Maintenance?"
"Periodically confirming our understanding of each other. So misunderstandings don't accumulate."
Riku laughed. "Then today is also channel maintenance day."
"Indeed," Aoi said. "A stable channel is the result of effort."
The three quietly pledged to keep cherishing and maintaining their relationship channel.