comma vs no comma before 'where' / 'when' [meaning?, conjunction]

[Julianus]

Hello.

1. a. That is the only basement where I put my books. b. That is the only basement, where I put my books.
2.a. I like Monday when we have to work hard. b. I like Monday, when we have to work hard.

As far as I know, 1(a) means that there is a possibility about existence of the extra basement. But 1(b) means that there is no possibility about existence of the extra basement.
Similary, 2(a) means that if he or she don't have to work hard on Monday, he or she may dislike Monday. But 2(b) means that he or she always like Monday.

Am I right?

Thank you always~.

 

[Istarion]

Hi Jullianus,
For sentence 1 you are right. Without the comma, "basement where I put my books" is a single unit, modified by "only" - there is only one basement in which I keep books, but as you say there may be other basements. I have underlined the elements which are modified by only. The comma alters the structure so that the unit being modified by "only" is just "basement".
Sentence 2 is similar, but I think it works much better if you use the plural "Mondays" (that's just a general point of English - I for one tend to say "I like Mondays" rather than "I like Monday").
"I like Mondays when we have to work hard" is likely to mean "I enjoy those Mondays on which we have to work hard" - there may be other Mondays which you do not enjoy. On the other hand, "I like Mondays, when we have to work hard" is more likely to mean as you suggest that you always like Mondays, and that you always have to work hard on Mondays. But this is much more ambiguous than sentence 1 I think - the meaning could switch depending on the context and the stress pattern of the sentence.
I hope that helps.
-I

 

[Chasint]

Julianus, in theory you are right, and we can detect the difference in textual form.

My problem is that these are artificial sentences that have been designed to look similar and create ambiguity. In life we would have to use unusually emphatic stresses to differentiate between these forms. In real English we make the difference clear by using different structures, e.g.

1a. That's the only basement I put my books in.
1b. That's the only basement; it's where I put my books.
2a. I like the Mondays when we have to work hard.
2b. I like Mondays - we have to work hard.

So for me this is a theoretical question only.

Note that I used BE. There may be subtle differences for AE.

 

[entangledbank]

Be warned that most people are careless about the commas, and while your distinctions are entirely correct, it is only the more careful writers who would consistently punctuate to show the distinction. The distinction itself is very real, and everyone would make it. I have to disagree with Biffo here: the distinction uses perfectly normal intonation, and at least sentences (2) are realistic examples. The comma indicates a fall and rise (meaning the sentence will continue with an addition) or a fall (meaning the main part of the sentence is over), and the part after it is a separate intonation phrase. Without a comma, it's all one intonation phrase, running levelly through that point. This is the same distinction as for defining and non-defining relative clauses with 'which' or 'who', where again a comma needs to be used to mark the clear distinction, but often isn't.