Never try to translate a patent claim in that case. I've known pharmaceutical patent claims to go for up to 30 pages with no full stop/period anywhere except right at the end! Apparently, it's because some judge in the 1800s thought it would be good and proper for each claim to be a single sentence. For some reason, no one has tried to overturn that notion in the century and something since.
Yeah, so is a strange word. It's a coordinating conjunction in this case. https://www.grammarly.com/blog/coordinating-conjunctions/
So is strange and it can act in a number of ways. For example this is a comma splice: I'm leaving town, so long and farewell. The "so" isn't a conjunction in this context. Another example that comes to mind is: You hated my performance, so be it.
You know what, @BayView, I'm wrong. It's not a conjunction in the use in question, it's an adverb. I still feel that as a parenthetical, the original sentence is fine.
There's a couple of English native speakers (US, UK) in the WordReference forum that still thinks: "Three is a number, so is four, but three is a prime number." is comma splicing. What should I tell them? ----Edit---- Ok, @Wreybies, you're right. (1) is correct from the POV of a USA speaker. Confirmed, then.
I'm glad we agree it's not a conjunction - I was having trouble wrapping my brain around that. I'm trying to think of a similar sentence, using a parenthetical, to the original #1, just to clarify it in my mind. Can you think of something with a similar structure? And are we agreeing that "So is four" can function as a grammatically complete sentence? If so the similar sentence would have to include a parenthetical that can function as a complete sentence... My dog is fat, he is immense, but he runs fast. > a parenthetical that's a complete sentence, but it doesn't feel correct to me even with the parenthetical understanding. If it were written in true parenthesis, I think I'd be okay with it > My dog is fat (he is immense) but he runs fast. > Well, I'm not really okay with it... I think it's ugly, but I'm not sure it's grammatically wrong? Is it because the parenthetic is inverted that it feels okay? Or is it because "So is four" really isn't a complete sentence... but it really feels like it is! Aaargh. Too early for grammar.
The original debate that made me post this comes from: (1) The hand is a body part, so is the arm, despite the hand being a feminine Spanish word and the arm a masculine one. In this case, I've been told there's comma splicing and the correct one would be: "The hand is a body part. So is the arm, despite the hand ..."
I don't like that sentence at all, but I think more for style/meaning rather than grammar. I'd rewrite it as something more like: "The hand and arm are both body parts; despite this similarity, "hand" is a feminine word in Spanish and "arm" is a masculine one." I mean, the arm isn't a body part despite being a masculine word. The original sentence, read literally, is very peculiar. But is the original actually wrong? I really have to squint hard to see that as a parenthetical. If we took out the possible parenthetical we'd have "The hand is a body part despite the hand being a feminine Spanish word and the arm a masculine one." It makes very little sense without the missing words... but I guess it's grammatically correct. I don't know. I sure don't like it! ETA: One of the things that makes it clear to me that "so" is not functioning as a conjunction in this sentence is that one of the ways I'd fix the sentence would be to add a conjunction. "The hand is a body part and so is the arm, despite..."
2 is correct. 1 is a run-on sentence. The problem that's confusing everyone is that "So is four" is a complete clause. It's not in normal SVO order, but that does happen sometimes. It's written as <verb-subject> instead of the expected <subject-verb>. Actually, it's <adverb-verb-subject>. Whatever. The point is, it's backwards. Like this example: He wants to eat. So do I. "So do I" is inverted. It's somewhat idiomatic. I hear too much of a finality after "Three is a number," so I wouldn't do a parenthetical there, though that would be an out if you could make it work. Maybe it's okay and it depends how you read it . . . It just doesn't work for my ear. I don't have any grammar books with me right now, so I can't list a real authoritative source. This is all I have: https://www.test-english.com/explanation/a2/so-neither/
@Artifacs Well done on finding the very edges of grammatical correctness with this one. It's fascinating. I still think my answer is correct, but as you can see this is far from an easy one to answer. The take-home here, as many have pointed out, is to avoid the parts of the map marked "Here be dragons!" and go with more conventional sentence structures.
So "so" is sort of like "also" on the other side of the mirror? "So is four." "Four is, also." "So do I." "I do, also." It's a theory. I don't know if I'll still like it in ten minutes.
The question that remains for me is whether there's a rule that parentheticals can't be complete sentences. I'm having trouble thinking of one that sounds right to me, but is that actually a rule?
In Spanish, we have a rule: if the sentence between two commas can be omitted without losing the whole sense of the speech, then it's ok to put it between commas. That's why (1) is ok in Spanish.
That's the general rule in English, too, but I don't think we say "the sentence between". We'd say "parenthetical elements" or something like that. This is why I'm not sure the parenthetical elements can actually be a full sentence/independent clause. Like: The dog, which was black, was hard to see at night. > fine But: The dog, it was black, was hard to see at night. > certainly doesn't seem fine to me. Now that @Seven Crowns has given me a bit of backup, I'm wavering back to my original opinion that the first example in the OP is a comma splice. My rationale (which I can't find supported anywhere, but which really feels right to me) is that a parenthetical element can't be an independent clause.
That's a big difference between English and Spanish. We don't care if it's a subordinate sentence, a simple sentence or a chunk of text. But I need to see your examples writen in Spanish, let me see. The dog, which was black, was hard to see at night. El perro, (el) que era negro, era difícil de ver de noche. Yep. It's Ok in Spanish. The dog, it was black, was hard to see at night. El perro, ese era negro, era difícil de ver de noche. Yep. It's Ok in Spanish.
BTW, @Artifacs, I'm Wreybies at wordreference too if you ever wish to say hello. I don't stay to chat there, though. It is the Vatican of Pedantry and I have no love for smug clergy. I ask my questions, get my answers, and then leave.
Nice to know, @Wreybies Chatting is not allowed there (only private conversations). I think they believe it jams his database or something. I also make the "in and out" procedure in the Only English forum and sometimes I stay a little to answer in the Spanish-English forum (Grammar and Vocabulary) and Only Spanish (There're some curious stuff there sometimes) What I don't like there is that the Moderators close a topic if it breaks some of the rules and they don't allow translations. The forum seems like Democracy, is not perfect but, hey, what else do we got? Anyway, It's great to have you there too. I'll give you a hug when I see you, buddy.
Both ways read fine to me. One would be more suited than the other depending on context. If I was writing for a character or a narrator that had a run-on cadence the first one would be just fine. Depending on how and why we are mentioning the number 4 all of a sudden makes a difference to me also. It is tough to say which is right when it is out of context. Taking the sentence on its own, I would just reword it to something like: Three and four are both numbers, but three happens to be a prime number.
