Daily puzzle

Conference Deductions

Edition #1 medium Publish date: 2026-01-16 Print
Scenario

Four developers gave talks on different topics and stayed at different hotels in four cities. Use the clues to match each person with their topic, hotel, and city.

Clues
  1. The developer who stayed at Garden Place was in Lisbon.
  2. The developer who spoke about MEV was in Prague.
  3. ZK Proofs was paired with Grand Hotel.
  4. Someone spoke about ZK Proofs and was in Oslo.
  5. Harbor Suites was not paired with Paris.
  6. No developer both spoke about Security and was in Oslo.
  7. It was not the case that the developer who spoke about MEV stayed at Metro Inn.
  8. Alice did not stay at either Grand Hotel or Metro Inn.
  9. Bob did not speak about either MEV or Security.
  10. Carlos was not in Lisbon or Prague.
  11. Diana did not stay at Metro Inn, and did not stay at Garden Place.
  12. Carlos was not in either Paris or Prague.
Solved

Explanation

Reveal the reasoning
  1. Begin with the cross-category links that lock two items together. Here, Clue 1, Clue 2, Clue 3 connect Talk Topic, Hotel, City.
  2. Clue 1 links Garden Place (Hotel) with Lisbon (City), so those two items must belong to the same developer.
  3. Clue 2 links MEV (Talk Topic) with Prague (City), so those two items must belong to the same developer.
  4. Clue 3 links ZK Proofs (Talk Topic) with Grand Hotel (Hotel), so those two items must belong to the same developer.
  5. Next, apply the elimination clues to shrink rows and columns before committing to any checks.
  6. Clue 8 rules out Grand Hotel and Metro Inn (Hotel) for Alice, which forces the remaining options.
  7. Clue 9 rules out MEV and Security (Talk Topic) for Bob, which forces the remaining options.
  8. Clue 10 rules out Lisbon and Prague (City) for Carlos, which forces the remaining options.

Solution

Show solution mapping

Solve the puzzle to reveal the full mapping.

Order: Talk Topic / Hotel / City

  • Alice -> Security / Garden Place / Lisbon
  • Bob -> DeFi / Metro Inn / Paris
  • Carlos -> ZK Proofs / Grand Hotel / Oslo
  • Diana -> MEV / Harbor Suites / Prague

About this puzzle

  • Published: 2026-01-16
  • Tags: traveleventslogic-grids
  • Validation: The puzzle JSON is validated at build time and a solver verifies there is a single intended solution.
  • Corrections: If you spot an issue, contact us with the puzzle date. See the editorial policy and the contact page.

FAQ

Do I need to guess?

No. Every GridCipher puzzle is designed to be solvable by deduction alone.

What is a good first step for Conference Deductions?

Start with clue 1. It locks in a concrete pairing between two categories, which you can immediately mark on the grid and use to eliminate other options. For example, it pairs Garden Place with Lisbon.

How do I mark a cell?

Click or tap a cell to cycle blank -> X -> check. Use X for no and check for the confirmed match.

Yes marks 0
No marks 0
Time 00:00
Status In progress
✓ = yes ✕ = no Blank = unknown

Tip: Shift-click or right-click to clear a cell quickly.

Developer x Talk Topic

Developer ZK Proofs DeFi MEV Security
Alice
Bob
Carlos
Diana

Developer x Hotel

Developer Grand Hotel Metro Inn Harbor Suites Garden Place
Alice
Bob
Carlos
Diana

Developer x City

Developer Paris Lisbon Oslo Prague
Alice
Bob
Carlos
Diana

Keep solving

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Up next: Cafeteria Choices (2026-01-17)

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