Alternative headline from "fish fish fish eat eat eat" [1,2]:
Hitman hitman hitman hitman hitman hires hires hires hires hired
[1] https://news.ycombinator.com/item?id=231097
[2] https://jakubmarian.com/fish-fish-fish-eat-eat-eat-is-a-gram...
Hitman hitman hitman hitman hitman hires hires hires hires hired
[1] https://news.ycombinator.com/item?id=231097
[2] https://jakubmarian.com/fish-fish-fish-eat-eat-eat-is-a-gram...
Fish [that] fish eat eat [food].
That works because the second "eat" is in the present indicative. But you can't stack those. With three "eat"s, the second one needs to be followed by an object, not another verb.
That's why the buffalo sentence works: Buffalo(n) [that other] buffalo(n) buffalo(v) [themselves] buffalo(v) buffalo(n).
Fish [that] fish [that] fish eat eat... eat.
You have a compound noun "fish [that] fish eat". Call that X. Then you have a larger compound noun, "fish [that] X eat". And as with the original you can tack an 'eat' on the end as those fish eat some unspecified food. Of course you can then go further and define Y as "fish that X eat", etc. It can be infinitely recursed.
"Fish fish eat" is indeed a sensible noun phrase. And we can make that noun a subject of the verb eat. But "fish fish eat eat" is not a noun phrase, and we can't make it the subject nor the object of a further "eat".
(1): X' = fish X eat ("fish that X eats")
You can continue forever by repeatedly applying equation (1) to make bigger and bigger noun phrases. Producing:
(2): X = fish fish eat
(3): X' = fish {fish fish eat} eat
(4): X'' = fish {fish {fish fish eat} eat} eat
At the end of which you can stick an "eat" on the end to make a sentence.
It would be nice if English worked recursively like that, but it doesn't. Maybe I was wrong in focusing on the verbs; the problem is also stacking nouns the way the sentence does. By splitting the object, subject, and verb so dramatically, the sentence doesn't end up making sense.
Obviously if you take it as axiomatic that this algorithm does work, then you can keep claiming it's grammatical. But even the first round (fish fish fish eat eat) doesn't add up. The word "that" isn't a mere helper; there is no English sentence in which "fish fish fish" (all as nouns) can make sense.
I'm not sure how to demonstrate this any more clearly than it already has been, but I'll try one last time. "fish that fish eat" is a compound noun. I think we agree on that. And you can shorten that to "fish fish eat", and it's still a grammatically correct noun. "fish fish eat" is a thing. Now you can build a sentence around that thing. For example, "The water fish fish eat swim in is cold." Right? It's easiest to parse if you say the 'fish fish eat' noun more quickly than the rest of the sentence, like, "The water fish-fish-eat swim in is cold."
Of course, we can replace the noun water there with more fish! "The fish fish fish eat swim with are small." In fact, you don't need the 'the' there. "Fish fish fish eat swim with are small," works too. As does, "Fish fish fish eat eat are also small." Note we just replaced 'swim with' with 'eat' there. Now we have actually built a larger compound noun, "Fish fish fish eat eat." Finally, we can replace the verb 'are' at the end and we get, "Fish fish fish eat eat eat," a grammatically correct sentence.
Does that help?
https://www.google.com/search?sxsrf=ACYBGNSVOGMnms9RKigZTLds...