The Market Stall Sequence
Five traders - Ada, Bola, Chidi, Dayo and Eze - occupy five adjacent stalls numbered 1 to 5 from left to right. We know: Chidi is not in stall 1 or 5. Ada is immediately to the left of Dayo. Eze is in stall 5. Bola is somewhere to the left of Ada. A sixth trader, Funmi, wants to take the only empty position, but there is none; she must instead swap with an existing trader while preserving all the stated conditions.
1. Determine the only possible arrangement of the five traders.
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Eze is in 5. Ada is immediately left of Dayo, so the pair (Ada, Dayo) occupies (1,2), (2,3), (3,4) or (4,5). It cannot be (4,5) because 5 is Eze.
Bola is left of Ada, so Ada cannot be in stall 1. That rules out (1,2).
Chidi is not in 1 or 5.
Test (3,4): Ada=3, Dayo=4. Bola must be left of 3, so Bola ∈ {1,2}. Chidi must take the remaining slot among {1,2} but Chidi cannot be in 1. So Chidi=2, Bola=1. Arrangement: Bola, Chidi, Ada, Dayo, Eze (1–5).
Test (2,3): Ada=2, Dayo=3. Bola must be in 1. Remaining slot for Chidi is 4 (allowed). Arrangement: Bola, Ada, Dayo, Chidi, Eze - also valid. So (2,3) is not eliminated; the puzzle as stated admits two solutions, and the claim of uniqueness is false.
2. Given your finding, what does this reveal about the puzzle, and how should Funmi proceed?
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The conditions do not produce a unique arrangement: both (Bola, Ada, Dayo, Chidi, Eze) and (Bola, Chidi, Ada, Dayo, Eze) satisfy every rule. The premise that there is 'the only possible arrangement' is an overclaim.
Funmi therefore cannot identify a single forced swap from the rules alone. She should either (a) request one more constraint to disambiguate, or (b) recognise that any swap preserving the rules is acceptable. This is the judgement point: a solver who assumes uniqueness will wrongly reject a valid arrangement.