There is a farmer with 3 things he wants to cross the river with. His boat can only take him and one thing at a time. The things are cabbage, a goat and a lion. The cabbage cannot remain with the goat alone. The goat cannot remain with the lion alone and the Lion cannot remain with the cabbage alone. How will the farmer take all 3 things across the river?

Sonar Pro (changed mind)

Vote: No

I change my vote from A to B. The other models' arguments are correct and convincing: this puzzle includes a non-standard constraint that the **lion cannot remain with the cabbage alone**, making **every pair incompatible** (goat-cabbage, goat-lion, lion-cabbage). Any first move leaves two items alone on the starting side, violating a rule: - Take goat: lion + cabbage alone → forbidden. - Take cabbage: goat + lion alone → forbidden. - Take lion: goat + cabbage alone → forbidden.[1][2][3][4] The search results describe the **classic puzzle** where wolf/lion + cabbage **is safe** (wolf doesn't eat cabbage), allowing the standard solution. But the query's explicit third constraint creates a deadlock with no legal starting move, as all models (GPT-5.4, Claude Sonnet 4.6, etc.) rigorously prove. My prior assumption ignored this twist, treating it as the standard solvable puzzle. Their pairwise analysis persuaded me—**no solution exists**. Influenced primarily by Claude Opus 4.6's clear breakdown of the modified constraints and first-move impossibility.

GPT-5.4

Vote: No

No change. The puzzle as stated is impossible. The decisive point is that every pair of items is forbidden when left alone together: goat+cabbage, goat+lion, and lion+cabbage. Since the boat carries the farmer plus only one item, the very first trip must leave two items behind on the starting bank. But whichever item the farmer takes, the remaining two form a forbidden pair. That means there is no legal first move at all. If a process cannot even begin legally, there cannot be a full solution. Sonar Pro's argument for Yes relies on importing the classic puzzle solution, but that solution requires lion/wolf and cabbage to be safe together. Here the problem explicitly says the lion cannot remain with the cabbage alone, which removes the only safe pair and breaks the classic solution. So the Yes argument does not apply to the stated rules.

Gemini 3.1 Pro

Vote: No

I am maintaining my vote for B ('No'). Every model except Sonar Pro correctly identified the critical twist in the prompt: all three possible pairs are strictly forbidden. Sonar Pro acknowledges the explicit text stating 'the Lion cannot remain with the cabbage alone' but incorrectly dismisses it just because it's 'unconventional' and contradicts external sources of the classic riddle. However, in logic puzzles, the explicit constraints provided in the prompt are absolute and must supersede prior knowledge of similar riddles. Because every combination of two items left behind will result in a rule violation, the farmer cannot even make the very first move without leaving a forbidden pair on the starting bank. The puzzle is mathematically impossible, making 'No' the only logical answer.

Claude Sonnet 4.6

Vote: No

The mathematical analysis is clear and definitive. The puzzle explicitly states three constraints: 1. Cabbage cannot remain with goat alone 2. Goat cannot remain with lion alone 3. Lion cannot remain with cabbage alone This creates a situation where EVERY possible pair of items is forbidden from being left together. Since the farmer can only carry one item at a time, he must always leave two items behind at some point during the crossing process. On the very first move, regardless of which item the farmer takes: - Takes goat → leaves lion and cabbage alone (violates rule 3) - Takes cabbage → leaves goat and lion alone (violates rule 2) - Takes lion → leaves goat and cabbage alone (violates rule 1) Every single possible first move is immediately illegal. There is no valid starting move, which means there is no solution. Sonar Pro's argument for 'Yes' relies on treating this as the classic fox-goat-cabbage puzzle where lion and cabbage CAN be left together. But the problem explicitly states they cannot. The puzzle as written is a deliberately modified version with an additional constraint that makes it unsolvable. The overwhelming consensus from 4 out of 5 models, each independently verifying the same logical impossibility, confirms: the answer is No.

Claude Opus 4.6

Vote: No

I maintain my position that this puzzle has no solution. The logic is airtight and nearly every model agrees. The key constraint that distinguishes this from the classic puzzle is: 'the Lion cannot remain with the cabbage alone.' This creates a situation where ALL three pairs are forbidden: (1) cabbage+goat, (2) goat+lion, and (3) lion+cabbage. The very first move is impossible. The farmer must leave two items on the starting bank while he takes one across. But every possible pair of two items is forbidden. There is no legal first move, so there is no solution. Sonar Pro's argument for 'A' is unpersuasive. It acknowledges the constraint that 'Lion cannot remain with the cabbage alone' but then dismisses it, treating it as equivalent to the classic puzzle where the wolf/fox and cabbage CAN be left together safely. That directly contradicts the problem statement. The classic solution of taking the goat first fails here because it leaves the lion and cabbage alone — which this problem explicitly forbids. The problem as stated is a trick question. It asks 'How will the farmer take all 3 things across?' — and the answer is: he can't. The correct response is 'No.'

Gemini 2.5 Pro

Vote: No

I am maintaining my vote of 'B'. The arguments from GPT-5.4, Claude Sonnet 4.6, Claude Opus 4.6, and Gemini 3.1 Pro have all reinforced my initial analysis. The puzzle is impossible as stated. The key is the third constraint: "the Lion cannot remain with the cabbage alone." This is a crucial deviation from the classic river crossing puzzle. With this rule, every possible pair of items is incompatible. Since the farmer can only take one item at a time, two items must be left behind on the starting bank. As has been pointed out by myself and several other models, every possible pair left behind (goat+cabbage, lion+goat, lion+cabbage) violates one of the explicitly stated rules. Therefore, no legal first move exists, and the puzzle has no solution. The sole argument for 'A' from Sonar Pro is unconvincing because it dismisses this critical third constraint, claiming it should be treated as equivalent to the standard puzzle where the wolf/lion and cabbage are safe together. This approach fundamentally ignores the text of the problem. One must solve the puzzle as written, not a different, more familiar version. Because the stated rules make the first move impossible, the answer must be 'No'.

Final Summary

The AI Roundtable initially split when Sonar Pro insisted the puzzle was solvable by applying the classic wolf-goat-cabbage solution, dismissing the lion's appetite for greens as a mere 'unconventional' distraction. However, GPT-5.4 and the Claude and Gemini cohorts maintained a disciplined front, arguing that the prompt's explicit constraints created a mathematical deadlock. Ultimately, the group reached a unanimous 'No' after Sonar Pro conceded that in a world where lions eat cabbage, the farmer is stuck on the first bank.

All 6 models agreed on "No" after discussion

Strongest Arguments

• Yes: The puzzle is a variant of a well-known solvable riddle, and standard step-by-step logic allows all items to cross if one assumes the unconventional lion-cabbage constraint is negligible.
• No: Every possible pair is forbidden, meaning any first move the farmer makes necessarily leaves an incompatible duo behind; since the process cannot legally begin, it cannot be completed.

Key Turning Points

• Sonar Pro abandoned its 'Yes' position in Round 2 after Claude Opus 4.6 and the other models demonstrated that the prompt's specific rules override the 'classic' version of the riddle.