Simultaneous robot orders
Predict how two committed programs interact under a shared collision rule.
Cooperation & communication
- Players
- 2 players or 2 teams
- Time
- 15–20 minutes
- Materials
- 5×5 grid, two tokens and three order slots each.
Prepare
Red begins A1 aiming for E5, blue E5 aiming for A1. North increases row, east increases column. Each secretly writes three orders chosen from N,E,S,W and X for wait. These are absolute board directions, not turns relative to a token’s facing.
Play
Reveal both programs together. At each of three ticks calculate both proposed destinations from the current positions. An off-board proposal becomes a wait. If both propose the same square or propose to swap squares, both stay. Otherwise both move. Moving into a waiting opponent is also a same-square collision.
Worked example
For a practice collision put red B3 and blue D3. Red E and blue W both propose C3, so neither moves. With red B3 and blue C3, E/W proposes a swap and both stay. With red B3 and blue D3, E/X moves red to C3 and leaves blue at D3.
Finish and check
After each tick, a token on its target wins immediately; if both arrive on that tick, draw. Otherwise write new three-order programs. Stop after six programs each and draw if no target is reached. Players may not rewrite an order once revealed.
Adaptation and limits
Use a neutral recorder when working in teams. The collision practice uses a separate setup, so reset A1/E5 before a match. Untimed planning is default. Shared rules, not the dexterity of moving tokens first, decide the result.
Purpose, observation and provenance
Within this activity: Predict how two committed programs interact under a shared collision rule.
Check simultaneous proposals before moving either token.
Our rules, examples and printable diagrams are separately prepared. The earliest inventor of the broader mechanism is not established here.
Free alternative: Copy the supplied grids, labels and cards onto reused paper. No specialist product is needed. Adults may prepare pieces or act as a scribe.
Printable materials
Preview at 100% scale, with browser headers and footers off. Cut with suitable help. Keep host keys separate. This is a manual tabletop kit, not an online opponent, automatic judge or solver.
Player materials · Simultaneous robot orders
Start R:A1→E5; B:E5→A1. Program 1 ___ ___ ___ .
Tick / old R,B / proposed R,B / collision? / new R,B.
Player record · keep the host key separate
| Tick | Old R/B | Proposed R/B | New R/B |
|---|---|---|---|
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
| ________ | ________ | ________ | ________ |
Host key · separate from players
B3/D3 with E/W both stay. B3/C3 with E/W both stay. B3/D3 E/X→C3/D3.
Run the round
Red begins A1 aiming for E5, blue E5 aiming for A1. North increases row, east increases column. Each secretly writes three orders chosen from N,E,S,W and X for wait. These are absolute board directions, not turns relative to a token’s facing.
Reveal both programs together. At each of three ticks calculate both proposed destinations from the current positions. An off-board proposal becomes a wait. If both propose the same square or propose to swap squares, both stay. Otherwise both move. Moving into a waiting opponent is also a same-square collision.
For a practice collision put red B3 and blue D3. Red E and blue W both propose C3, so neither moves. With red B3 and blue C3, E/W proposes a swap and both stay. With red B3 and blue D3, E/X moves red to C3 and leaves blue at D3.
After each tick, a token on its target wins immediately; if both arrive on that tick, draw. Otherwise write new three-order programs. Stop after six programs each and draw if no target is reached. Players may not rewrite an order once revealed.
Use a neutral recorder when working in teams. The collision practice uses a separate setup, so reset A1/E5 before a match. Untimed planning is default. Shared rules, not the dexterity of moving tokens first, decide the result.
Related activities
Activity library · Robot route program: rules and printable materials