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Case 48: who took the Medieval Codex?
A routine inventory at the library has revealed that the Medieval Codex, officially listed as being in the Periodicals Room, is nowhere to be found. The insurance company won't pay a cent without a named culprit, so the pressure to solve this is real. Help the police unmask the thief.
The board
- 1Children's Room
- 2Vault
- 3Reception Area
- 4Storage Room
- 5Archive
- 6Periodicals Room
- 7Lobby
- 8Café
- 9Restrooms
- 10Study Room
- 11Office
- 12Restoration Room
- Plant: no character can stand on its cell, but the stolen item can be there.
- Seat: anyone can be on it.
- Shelf: no character can stand on its cell, but the stolen item can be there.
- Table: nothing can be on its cell.
- Screen: nothing can be on its cell.
- Window: the blue line on a wall.
Suspects and clues
- NNoah
He's next to a shelf. - OOmar
He's not in the Vault, and he's in a corner. - EElena
She's in column B. - SSven
He's in the Storage Room. - IIvan
He's in row 11. - YYusuf
He's in the Lobby. - PPriya
She's 2 columns away from the Restrooms. - HHana
She's 8 rows away from the Storage Room. - BBoris
He's 6 rows away from the Children's Room. - MMedieval Codex (stolen item)
It's right next to the Children's Room.
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
- Noah's clue: He's next to a shelf. 5 cells remain possible: J2, I3, J4, C5 and D6.
- Omar's clue: He's not in the Vault, and he's in a corner. 49 cells remain possible.
- Elena's clue: She's in column B. 10 cells remain possible.
- Sven's clue: He's in the Storage Room. 3 cells remain possible: C1, D1 and E1.
- Ivan's clue: He's in row 11. 6 cells remain possible: A11, B11, E11, F11, I11 and J11.
- Yusuf's clue: He's in the Lobby. 8 cells remain possible.
- Priya's clue: She's 2 columns away from the Restrooms. 5 cells remain possible: E3, F4, G5, A6 and F6.
- Hana's clue: She's 8 rows away from the Storage Room. It leaves a single cell: C9.
- Boris's clue: He's 6 rows away from the Children's Room. 2 cells remain possible: E4 and F4.
- The stolen item's clue: It's right next to the Children's Room. 8 cells remain possible.
- Hana can only be on C9. No one else can be in row 9 or column C, and no other character can be in the Reception Area.
- Every cell still open to Elena is in column B, so no one else can be in that column.
- Every cell still open to Sven is in row 1, so no one else can be in that row.
- Every cell still open to Ivan is in row 11, so no one else can be in that row.
- Every cell still open to Yusuf is in row 2, so no one else can be in that row.
- Every cell still open to Boris is in row 4, so no one else can be in that row.
- Every cell still open to Boris is in the Archive, so no other character can be there.
- Every cell still open to Priya is in row 6, so no one else can be in that row.
- J2, J4, C5 and D6 have already been ruled out, so Noah can only be on I3. No one else can be in row 3 or column I, and no other character can be in the Restoration Room.
- Proof by contradiction. Suppose Yusuf were on G2. Following the rules above, there wouldn't be enough columns left for everyone. So Yusuf is not on G2.
- F1, G1, H1, I1, J1, K1 and G2 have already been ruled out, so Yusuf can only be on H2.
- Proof by contradiction. Suppose Ivan were on E11. Following the rules above, there wouldn't be enough columns left for everyone. So Ivan is not on E11.
- Proof by contradiction. Suppose Ivan were on F11. Following the rules above, there wouldn't be enough columns left for everyone. So Ivan is not on F11.
- A11, B11, E11, F11 and I11 have already been ruled out, so Ivan can only be on J11. No one else can be in row 11 or column J, and no other character can be in the Vault.
- E3, F4, G5 and F6 have already been ruled out, so Priya can only be on A6. No one else can be in row 6 or column A, and no other character can be in the Periodicals Room.
- Every other cell the clue allowed has already been ruled out, so Elena can only be on B5. No one else can be in row 5 or column B, and no other character can be in the Restrooms.
- Every cell still open to Omar is in row 10, so no one else can be in that row.
- F9, G9, E10, F10, G10, E11 and F11 have already been ruled out, so the Medieval Codex can only be on G8. No one else can be in row 8 or column G.
- Every other cell the clue allowed has already been ruled out, so Omar can only be on E10. No one else can be in row 10 or column E, and no other character can be in the Children's Room.
- C1 and E1 have already been ruled out, so Sven can only be on D1.
- E4 has already been ruled out, so Boris can only be on F4.
Conclusion: Ivan is the only person sharing the Vault with the Medieval Codex, which is on G8. He is the thief.