"This book is about a woman, her husband, and their child."
Translation:Tato kniha je o ženě, jejím muži a jejich dítěti.
The sentence is talking about 'their' child, therefore: jejich (with short i.) This pronoun is not declined. (Yay!)
Jejím (with long i) is locative singular form of její ('hers')
Jejích (with long i) is locative plural form of její ('hers')
Pay attention to accents ;)
I wrote: « Tato kniha je o zene, jejím manzelovi a svých diteti. » (Yes I know, I should care more about the accents, but while I know where to place which, not all of them are possible to be added via the numbers block on the keyboard) and it was rejected to my surprise. If I remember correctly, “svých” should refer to the sentence's subjects' personal possessions, in this case the child they bring up. Why can't it thus be a possible pronoun? Why only “jejich”? Did I miss something in the respective course's Tips & Notes?
EDIT: In case anyone should object to the missing diacritics and claim them to be the reason for the rejection: I used the very same sentence, firstly with “svých” (Rejected), then “Jejich” (Accepted), so that it could only be the possessive pronoun that led to the rejection. It also was underlined in the correction.
Still? Because with all due respect, to see your enormous streak and the fact that I never saw you lower than at 25 with Czech on Duolingo, I thought that you may finally have mastered the language and would not step into such mistakes. Indeed, the language is almost ludicrously difficult!
Other than the subject being "kniha", as BoneheadBass noted, it's also worth noting that the correct form of "svůj" here would be "o svém dítěti" (locative singular) - cf. with "o mém/tvém/jejím/našem/vašem dítěti". If it was plural children, then it would be "o svých dětech". So, "o svých dítěti" is a number-mismatch.
It may also be interesting to note that when I read the sentence "Tato kniha je o ženě, jejím manželovi a svém dítěti" - I automatically interpret the "svůj" as referring back to the child instead of to the book, not sure why, possibly because a book can't have children and/or because the pronoun is so far removed from the subject. It doesn't make the sentence less ridiculous of course. "Svoje dítě" is a sci-fi time-travelling notion :D For example, there was an episode of Red Dwarf (a British sci-fi sitcom show) where the main character, Lister, discovered he was his own son (Lister je svůj syn.)
The wrong usage of "svůj" can lead to funny images, some of them almost like zen koans. Even the simple "Je to svoje." (instead of moje or tvoje) bends the mind a little.
Idiomatically, saying that someone is "svůj" (František je svůj) means that he is of his own kind, specific in his own way without trying to conform. But saying "Ten stůl je svůj" is a little mind-boggling. (The normal way of saying that the table doesn't belong to anyone would be "Ten stůl není ničí." (= is nobody's) or, of course, simply the literal "Ten stůl nikomu nepatří.")
Now I feel especially stupid for not having written svém dítěti. And this only one day ago... Well, I think I should stick with the alternative dziecko, it's easier to remember and to conjugate, and also has been accepted beforehand when I accidentally used it instead of the more original dítěti. (I.e. original in relation to the Czech language. But I think it may also be applied in Russian, although I had to check it up first) (EDIT: Yes it is, but it seems to be marked as colloquial, for whatever reason)
Unfortunately, I don't understand how you referred the “svůj” back to the child. I can clearly relate it to the woman, simply because the husband referred to her as well. (Now that I think of it, the “jejím” should also be switched to ta “svém”, since we are here, discussing why I am wrong in this idea.)
How on earth could someone be his/her own child? How would you bear yourself? :'D Even if you could travel through time, it remained impossible simply because you cannot be born when you were not yet born, especially when you are your own bearer. :D
As for the “Je to svoje”, not necessarily—it sounds like a very individualist thing to say: That you are yourself alone, and no-one else's. You do not owe anything to anybody, you are a free being. Still, I get the idea of your latter example, as it should be limited to sentient beings, or more technically to human beings as we are the only ones with the complex concept of possessions and ownership. A table cannot be itself as it is not a living being, lest a sentient being with a concept of private property.
Well, "dziecko" looks Polish. The Czech equivalent is "děcko". You can surely use it instead of "dítě", just be aware that it's colloquial, not as neutral and not as common as "dítě". It's not really used for "offspring", just for "kid" in general, that's also why "děcko" is not accepted in this exercise. It's admirable that you're learning Czech and Polish simultaneously, if a little masochistic, it must instill quite a confusion.
There's nothing much to understand about why I find it referring "back" to the child. Just telling you that the native speaker's impression upon reading/hearing "Tato kniha je o ženě, jejím manželovi a svém dítěti" is that the child is somehow its own, even though technically/grammatically it should be the book's child. The idea that it's the book's child comes to my mind second, while the idea that it should be the woman's child or both parents' child doesn't occur to me (until I start thinking about the sentence being incorrect) - probably because I would totally expect "jejím" or "jejich" there, respectively, never "svém".
As for being one's own child, that idea can be explained multiple way but it's always a paradox. Besides Red Dwarf, I'm sure there are other comical sci-fi works that explore it. In Futurama, for example, Fry is his own grandfather, also due to time travelling, of course.
As you can see by your last paragraph, using "svůj" (wrongly/atypically) can lead to philosophy - that was my point.
Thanks for hinting that at me, that the equivalent to dziecko is a rather colloquial expression and may not be commonly accepted in this course. In case it should be accepted when I type it in accidentally, I will report it as a mistake. In the end, to learn a more formal language may help to be understood generally even as a learner.
Thanks for calling it admirable; the longer I proceed, the more I tend to call it adventurous, if not downright stupid, but I can cope with it. In the end, I began to learn the two of them in tandem because I thought that they were at least slightly as close as Czech and Slovak are, at least in the foundational principles of syntax, grammar and vocabulary. As it turned out, I was wrong, and began to see Polish as easier to learn and understand, as Czech has such a loose syntactical structure and such a peculiar morphology. Its endings usually appear German, while the rest of the word appears unique to the Czech language. I just hoped that the endings for nouns and adjectives were more distinct, so that they were easier to remember. In Polish, you can almost safely tell one case from the other, while there are more interchangeable endings in Czech. All in all, I hope that I will eventually understand Czech as well as Polish, although I always feel stupid whenever I ask a question in either language's comments, and still I have to catch up with my vocabulary in both...
Ah, now I see what you mean! Maybe, at first reading, I still rejected to believe that Tato kniha could be the subject, and not either the woman or the husband. Upon accepting the fact, I see what you mean, but personally, I would then too choose jejich, as the child is not exclusively the woman's but also her husband's, unless they divorced and she received the full custody because the father behaved abusive. But why would she still call him her manželovi? Questions...
The concept of being one's own grandfather can be explained somehow, not biologically but in terms of family hierarchies. In German, there are entire songs about how one could become one's own grandfather, or as we call it: One's family tree ended up as a circle. In case you would like to hear them (two in total exist), I could link them hereby, but I don't know if you are fond of the German language. Your progress on DL mentions that you're halfway through, so you may be able to get through the lyrics, with a little dedication to look up unknown vocabulary.
Well, I did not expect philosophical concepts to come up, but good to know about the possibilities with this pronoun. In the end, there exist no similar ones in the non-Slavic languages I know. (Roman languages and Germanic ones)
You shouldn't feel stupid when you ask questions in the Czech or the Polish forum. You're learning two complex languages, it's totally expected that you would make mistakes and ask questions.
I learned German at high school, I only use Duo occasionally to brush up on it, since I never get to use it actively. I'll gladly read the songs if you provide a link.
About the reflexive possessive pronoun - actually Swedish has one: "sin" (from the same ancestor as German "sein"), but it's only used in the 3rd person (plural and singular). So they have "hans" (his), "hennes" (her), "dess" (its), "deras" (their), and then "sin" meaning "his/her/its/their own" depending on the subject.
But yeah, Slavic languages kept the full-fledged reflexive possessive. The Czech "svůj" comes from Proto-Slavic "svojь", which comes from (reconstructed/probable) Proto-Indo-European "swoyos".
Latin has a reflexive poss. "suus" but only uses it in the 3rd person, like Swedish.