[alister]

As a quick test of logical reasoning and basic Wikipedia-level knowledge, I asked Mistral AI the following question:

A Brazilian citizen is flying from Sao Paulo to Paris, with a connection in Lisbon. Does he need to clear immigration in Lisbon or in Paris or in both cities or in neither city?

Mistral AI said that "immigration control will only be cleared in Paris," which I think is wrong.

After I pointed it to the Wikipedia article on this topic[1], it corrected itself to say that "immigration control will be cleared in Lisbon, the first point of entry into the Schengen Area."

I tried the same question with Meta AI (Llama 4) and it did much worse: It said that the traveler "wouldn't need to clear immigration in either Lisbon or Paris, given the flight connections are within the Schengen Area", which is completely incorrect.

I'd be interested to hear if other LLMs give a correct answer.

[1] https://en.wikipedia.org/wiki/Schengen_Area#Air_travel

[mcintyre1994]

I think Gemini's answer (2.5 Flash) is impressive

----

Since both Portugal and France are part of the Schengen Area, and a Brazilian citizen generally does not need a visa for short stays (up to 90 days in any 180-day period) in the Schengen Area, here's how immigration will work:

Lisbon: The Brazilian citizen will need to clear immigration in Lisbon. This is because Lisbon is the first point of entry into the Schengen Area. At this point, their passport will be stamped, and they will be officially admitted into the Schengen Zone.

Paris: Once they have cleared immigration in Lisbon, their flight from Lisbon to Paris is considered a domestic flight within the Schengen Area. Therefore, they will not need to clear immigration again in Paris.

Important Note: While Brazilians currently enjoy visa-free travel, the European Travel Information and Authorization System (ETIAS) is expected to become mandatory by late 2026. Once implemented, Brazilian citizens will need to obtain this electronic authorization before their trip to Europe, even for visa-free stays. However, this is a pre-travel authorization, not a visa in the traditional sense, and the immigration clearance process at the first point of entry would remain the same.

[viraptor]

It looks like you're not sure of the answer yourself. That's really not a good way to test the LLMs. You'll just prefer the one that convinces you the most rather than the correct one.

[schneehertz]

This is deepseek-r1's answer:

```

Based on the Schengen Area rules for international travel:

Lisbon (Portugal) - Immigration clearance is required here. Since Lisbon is the first point of entry into the Schengen Area (and Brazil is outside Schengen), the passenger must clear immigration (passport control) in Lisbon. This is standard for all non-Schengen arrivals.

Paris (France) - No immigration clearance is needed. After clearing immigration in Lisbon, the onward flight to Paris is considered a domestic Schengen flight (no border checks within Schengen).

```

[jaza]

Sounds to me like "immigration in Lisbon or in Paris or in both cities or in neither city" is a trick question, because (on top of immigration in Lisbon as the Schengen entry point) surely the traveller also needs to clear immigration in Sao Paulo (as the Brazil / Mercosur exit point)?

[eigenspace]

I wonder if they adjusted it since reading this thread, or if you forgot to turn on reasoning or if you just got unlucky. For me, when I ask this it thinks for about 1.5 minutes and responds with

"The Brazilian citizen needs to clear immigration in Lisbon."

When I asked it to explain why, it said

"The Brazilian citizen needs to clear immigration in Lisbon because Lisbon is the first Schengen entry point when traveling from a non-Schengen country (Brazil) to a Schengen country (France via Portugal). According to Schengen rules, travelers must clear immigration at the first Schengen port of entry. Since Paris is also within the Schengen Area, no additional immigration checks are required upon arrival in Paris."

[marsa]

doing some reason.. uhh intuitioning i imagine brazil and portugal might have some sort of a visa-free deal going on in which case llama 4 might actually be right here?

[mcintyre1994]

AFAIK Schengen has a common visa policy, so there couldn't be such a deal between Brazil and Portugal. It'd also be extremely surprising if two countries not in a common travel area had a deal where you didn't have to clear customs at all, I suspect that doesn't exist anywhere in the world.

[alister]

Brazilians don't need a visa for Portugal, France, or any Schengen country. But everybody has to pass through immigration control (at least a passport check even if you don't need a visa) when entering the Schengen zone. My question was which country would that happen in.