Roboku
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Case 25: who took the Ancient Treatise?
At closing time at the library, security confirmed that the Ancient Treatise was missing; it was last seen in the Archive. The cameras show nothing out of the ordinary, which points to someone who was already inside. Help the police unmask the thief.
The board
- 1Office
- 2Restrooms
- 3Vault
- 4Archive
- 5Lobby
- 6Children's Room
- 7Conference Room
- 8Café
- Plant: no character can stand on its cell, but the stolen item can be there.
- Seat: anyone can be on it.
- Table: nothing can be on its cell.
- Screen: nothing can be on its cell.
Suspects and clues
- LLucy
She's in row 1 and right next to the Restrooms. - CChidi
He's in a corner. - XXiomara
She's 1 row away from the Archive. - SSandra
She's in column D. - KKenji
He's in the Conference Room. - DDana
She's not in the Restrooms. - AAncient Treatise (stolen item)
It's 2 columns away from the Office.
Remember the rules: no two suspects (nor the item) ever share a row or a column, each character is in a different room, and the thief is the only one sharing a room with the stolen item. Unsure? Read how to play and the clue types.
Solution
Try it yourself first: pen and paper are enough. When you want to check, open the reasoned solution.
Show the step-by-step solution
- Lucy's clue: She's in row 1 and right next to the Restrooms. It leaves a single cell: C1.
- Chidi's clue: He's in a corner. 28 cells remain possible.
- Xiomara's clue: She's 1 row away from the Archive. It leaves a single cell: E4.
- Sandra's clue: She's in column D. 7 cells remain possible.
- Kenji's clue: He's in the Conference Room. 4 cells remain possible: A5, A6, A7 and B7.
- Dana's clue: She's not in the Restrooms. 34 cells remain possible.
- The stolen item's clue: It's 2 columns away from the Office. 2 cells remain possible: F6 and B7.
- Lucy can only be on C1. No one else can be in row 1 or column C, and no other character can be in the Lobby.
- Xiomara can only be on E4. No one else can be in row 4 or column E, and no other character can be in the Café.
- There are as many suspects (counting the item) as rows, so each row holds exactly one. Only Chidi can still reach row 3, so that is where he must be.
- Every other cell the clue allowed has already been ruled out, so Chidi can only be on B3. No one else can be in row 3 or column B, and no other character can be in the Restrooms.
- B7 has already been ruled out, so the Ancient Treatise can only be on F6. No one else can be in row 6 or column F.
- There are as many suspects (counting the item) as columns, so each column holds exactly one. Only Dana can still reach column G, so that is where she must be.
- The Ancient Treatise can only be in the Children's Room, and Dana is the only character who can still get in there. Since the thief shares a room with the item, Dana must be in the Children's Room.
- Every other cell the clue allowed has already been ruled out, so Dana can only be on G5. No one else can be in row 5 or column G, and no other character can be in the Children's Room.
- A5, A6 and B7 have already been ruled out, so Kenji can only be on A7. No one else can be in row 7 or column A, and no other character can be in the Conference Room.
- D1, D3, D4, D5, D6 and D7 have already been ruled out, so Sandra can only be on D2.
Conclusion: Dana is the only person sharing the Children's Room with the Ancient Treatise, which is on F6. She is the thief.