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Schubert's Steamroller
Wolves, foxes, birds, caterpillars, and snails are animals, and there are some of each. Also there are some grains, and grains are plants.
Every animal either likes to eat all plants, or, all animals much smaller than itself that like to eat some plants.
Caterpillars and snails are much smaller than birds, which are much smaller than foxes, which in turn are much smaller than wolves. Wolves do not like to eat foxes or grains, while birds like to eat caterpillars but not snails. Caterpillars and snails like to eat some plants.
Therefore there is an animal that likes to eat a grain-eating animal. What is it?
Every animal either likes to eat all plants, or, all animals much smaller than itself that like to eat some plants.
Caterpillars and snails are much smaller than birds, which are much smaller than foxes, which in turn are much smaller than wolves. Wolves do not like to eat foxes or grains, while birds like to eat caterpillars but not snails. Caterpillars and snails like to eat some plants.
Therefore there is an animal that likes to eat a grain-eating animal. What is it?
Answer
The fox likes to eat the bird which likes to eat the grain.Reason:
The bird is a plant eating animal because it does not like to eat snails, which like to eat some plant, so it does not like to eat ALL such animals.
Therefore it must like to eat all plants.
The fox is not a plant eating animal, because the wolf does not like to eat all plants (specifically grain), and therefore must like eating all animals which like to eat some plants.
But it does not like to eat foxes.
Therefore foxes cannot be animals which like to eat some plant.
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Comments
Nicely done!
confusing, but nicely done
Wolves are another answer: because
the wolves do not like to eat grain,
they must like to eat all animals
much smaller than themselves who like to
eat some plants, which means they must like
to eat birds, which we know like to eat grain,
as in the original solution. This assumes that
the relation "much smaller" is transitive, which it
is in the ordinary meaning of "much smaller." (I.e.,
because birds are much smaller than foxes and foxes are
much smaller than wolves, it follows that birds are much smaller
than wolves.)
the wolves do not like to eat grain,
they must like to eat all animals
much smaller than themselves who like to
eat some plants, which means they must like
to eat birds, which we know like to eat grain,
as in the original solution. This assumes that
the relation "much smaller" is transitive, which it
is in the ordinary meaning of "much smaller." (I.e.,
because birds are much smaller than foxes and foxes are
much smaller than wolves, it follows that birds are much smaller
than wolves.)
that was very good, thanks
the wording and grammar of this line kept me from even being able to understand what it was I was supposed to be looking for: "Every animal either likes to eat all plants, or, all animals much smaller than itself that like to eat some plants."
There are several birds that eat snails! Thrushes, Blackbirds - and seagulls eat limpets, which must be related to snails.
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