The Dome

The Great Library · closing time · a whisper under the dome · Difficulty: Chief 10 · 16×16

Closing time at the Great Library. Under the famous dome the last readers were still bent over their desks when the porter’s bell rang – and when the lights came up again, Valerian, the head librarian, lay dead in the Manuscript Alcove. The dome is a whispering gallery: any sound made on the reading floor is carried to exactly one spot – the square opposite it through the centre of the hall – and to nowhere else. Every suspect has told the inspector where they were and what, or whom, they heard. Nobody heard the murderer. Find the one who was alone with Valerian.

Rules

1. The echo of the dome: the dome carries every sound to exactly one place – the square mirrored through the centre of the hall (row 17 − r, column 17 − c: the echo square of R3C6 is R14C11, and vice versa). Whoever was on that square heard the speaker, and nobody else did. Hearing is mutual: if she heard him, he heard her. “Heard nobody” = the echo square was empty (or holds an object); “heard a woman” = a woman was on the echo square; “heard Alma” = Alma was there. The victim could be heard too. Helper: select a square on the board and its echo square is outlined.
2. Nobody heard the murderer: the murderer’s echo square was empty. So everybody who heard somebody is innocent.
3. Every row and every column holds exactly one person. As soon as you place someone, cross out their whole row and column.
4. “Beside” = directly left, right, above or below, and in the same area. Squares with objects (desks, bookcases, shelves, the counters, statues, globes, the staircase…) cannot be occupied; the chairs, the armchairs, the bench and the doormat can.
5. Directions refer to rows and columns, not to the same line: “exactly one row north of him was a woman” = the person in the row directly above is a woman, in any column; “north of Alma” = in a row above hers.
6. The murderer was alone with the victim: nobody else was in that area.

Statements

• Alma (doctoral student): She was beside a desk. Of the people in her area, exactly one was a man.
• Balduin (historian): Exactly one row north of him was a man. A shelf was somewhere in his row.
• Cuthbert (retired judge): There was no other man in his area. He heard a member of the library staff.
• Dominika (poet): A counter was somewhere in her row. A bookcase was somewhere in her row.
• Eberhard (law student): He heard Alma. A chair was somewhere in his column.
• Felicitas (genealogist): A coat rack was somewhere in her column. She was alone with a man.
• Gunther (deputy librarian): He was the only man beside a chair. A chair was somewhere in his column.
• Honora (reference librarian): She was alone in her area. A chair was somewhere in her column.
• Igor (night porter): He was the only man beside the plant. He heard nobody.
• Jutta (cataloguer): The bench was somewhere in her column. Somebody else was beside the same chair as her.
• Kristof (bookbinder): A bookcase was somewhere in his area. There was exactly one other person in his area.
• Lavinia (architect surveying the dome): She was not beside a chair.
• Maude (journalist): She was in the Science Section. She was alone with a visitor.
• Nestor (antiquarian bookseller): He heard Honora.
• Ortrun (benefactor of the library): There was a woman in her area. She heard a reader.
• Valerian (head librarian): The victim. He was found in the Manuscript Alcove, beside a desk – alone with the murderer.

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