European tourist site, planting medium

It's Monday, and you Puzzlers know what that means. Welcome back to Natural Language Puzzling, the blog where we use natural language programming (NLP), language models and tools and good old fashioned linguistics to solve the weekly Sunday Puzzle from NPR. Here is this week's puzzle:

This week's challenge comes from listener Jessica Popp, of Indiana, Pa. Name a famous European tourist site in nine letters. Rearrange its last four letters to name something that its first five letters can be planted in.

It's been a few weeks since we've had a "normal" puzzle like this one. It follows the pattern of many Sunday Puzzles: take thing from category A, apply a prescribed transformation, get thing from category B.

In these kinds of puzzles, we often start with lists: a list for Category A and/or a list for Category B. Then we need some kind of function to apply the transformation. Finally, we either check to see if the result is in our list for Category B; if we don't have a list for Category B, we use some kind of language model to evaluate each transformed candidate in an appropriate context and see how well it fits.

This time around, we'll need:

• E: a list of European tourist sites
• we can search the web for existing lists
• we can ask a chatbot LLM to generate a list for us
• we can try to cobble one together ourselves
• we'll need to filter this list to only nine-letter entries
• Note that LLMs are still not very good at returning words of specified length
• P: a list of things that some unknown thing can be planted in
• this one probably makes sense to ask chatbot LLM for
• we could also query a non-chatbot LLM to fill in blanks for us
• again, we'll need to filter this by length--for 4-letter words this time
• functions/tools:
• from my reading of the puzzle, the first five letters of the European tourist site should be something that can be planted; thus, the first five letters alone should be a common noun, so we could start with a function that takes the first five letters of each item in list E and checks to see if they make a valid word.
• if we find a valid word, we can:
• generate all the permutations of the last four letters
• keep only those that are valid words
• use a sentence template or templates with an LLM to see how likely the candidates are in context, e.g.:
• I know the perfect [BLANK] to plant the new [BLANK] in.
• In theory, the solution would be among the candidate pairs that result in the lowest perplexity score from the above sentence.

This is the approach I'll be taking. How would you do things differently? Share your thoughts in the comments. I'll be back with an update after the Thursday NPR submission deadline (no spoilers here!) to share my scripts and my solution (if I manage one). Good luck!

The deadline for NPR submissions has passed, so click the spoiler button below to see my solution.

ACROPOLIS --> ACROP, SOIL