“Decision phase commencing,” ARK announced. “You have three minutes to choose: Sacrifice or Keep. Input your selection via the holographic interface. For unconscious subjects, the paired partner will decide for both.”

  “Once selections are locked, outcomes will be calcuted and dispyed.”

  “Begin.”

  A three?minute countdown appeared on the interface in Chamber Alpha.

  Yuma studied the options. Two buttons, glowing softly:

  SACRIFICE (Blue)

  KEEP (Red)

  Simple. Binary. Life?or?death.

  He looked at Sakuya. “Game theory analysis: In a one?shot prisoner’s dilemma with anonymous pairing, the dominant strategy is defection—Keep. But we’re not anonymous. We know each other’s psychological profiles. And the bonus structure makes mutual Sacrifice more profitable.”

  Sakuya nodded, his analytical mask firmly in pce. “Correct. Mutual Sacrifice yields +500 Points each. Mutual Keep yields ?50 each. The superior Pareto optimum is cooperation.”

  “But,” Yuma continued, “if one defects while the other cooperates, the defector gains +200 while the cooperator loses ?100. The temptation to defect exists.”

  “Only if you believe your partner will cooperate. If you defect while they also defect, you both lose. The risk?reward calcution favors cooperation—provided both parties are rational.”

  “Are you rational, Sakuya?”

  “Are you, Yuma?”

  They stared at each other, two mirrors of detached logic.

  Yuma’s mind ran the numbers. If Sakuya chooses Sacrifice:

  I choose Sacrifice: +500 each.

  I choose Keep: +200 for me, ?100 for him.

  If Sakuya chooses Keep:

  I choose Sacrifice: ?100 for me, +200 for him.

  I choose Keep: ?50 each.

  The Nash equilibrium is mutual Keep if we assume the other will defect. But if we can communicate—even implicitly—we can shift to mutual Sacrifice.

  Sakuya understands this. He’s as rational as I am.

  Probability he chooses Sacrifice: 85%.

  Probability I should choose Sacrifice: 92%.

  Yuma reached out and pressed SACRIFICE.

  Across the room, Sakuya did the same.

  The interface chimed.

  “Pair: Yuma & Sakuya. Both select: SACRIFICE.”

  “Outcome: No Point loss. Bonus: +500?P each.”

  Yuma’s wrist?tag updated: 1,740?P.

  Sakuya’s: 1,650?P.

  No words were exchanged. None were needed. They had both calcuted the optimum and arrived at the same conclusion.

  Rationality prevails, Yuma thought. For now.