"a weird thing"
Thank you very much for reminding me that ي can be a vowel or a semivowel. But because of the fatha on the ش, it wouldn't be shii, would it, it would be sha-ii, no? Should I have known that the ي was in the role of semivowel because it came after a vowel sound, albeit only a fatha? You can't have two vowels side by side in Arabic? Incidentally, when you say "declination", I suppose you mean declension? And doesn't that include the grammatical cases (together with number and gender)? At least, that's the case with the (Indo-european) languages I know.
Somehow yes, a fatHa there does signal that the coming letter has Sukún (most of the time but not necessarily, it can be another vowel). Usually we don't type the diacritics in our daily writing, we just know the words by heart.
If you mean by "two vowels side by side" as in diphthongs, well not really; Arabic has no diphthongs. Either a short vowel or a long one spread across 3 basic forms: A I U.
And yes, I meant declension, sorry. I picked the wrong word there.
Of course I know that most of the time you don't write the harakat. Believe me, that is the bane of non-Arab speakers, we don't need reminding! When I said "two vowels side by side" I didn't mean a diphthong, which I take to be the sort of sound you get in English in words like "take", "boy" ie a glide from one vowel to another, with the first vowel being pronounced with more definition than the second, or "yes", "we" where the second one is stronger. The point is, a diphthong forms only one syllable. In Russian, however, you do get two vowels side by side and they form two syllables. So you're telling me you never get this Russian thing in Arabic? That's good to know. And it was very salutary to remind me that the three long vowels also serve as semivowels (= semi-consonants). Oh, Alif doesn't, does it? Though it serves other purposes. Yes, it's confusing about declension. Declination is something in geometry, I think.
Yep, I've been following up with some of my interests in astronomy and Declination is used (along with the Right Ascension, RA, as a coordination system). I guess that's why I mixed up.
Yes, about the vowel thing. The thing is, we see it differently, under a different perspective, in spoken and written language. In Russian they do indeed have two vowels and by virtue in spoken language these vowels together might mark the end and the beginning of a syllable, or like in English as in Poet. In Arabic, the writing as you know is Abjadic, and thus if a "sound" is affected by a vowel then automatically we think of it as a consonant, and maybe this also stems from the way that we see how syllables in the language are formed (as a rule, syllables in Arabic cannot be a cluster of consonant nor start off with vowel-less consonant, CV(C) only). So, if I'm about to write Poet in Arabic, I naturally think of: Pu-wit.
Anyway, I guess this is not something to worry about as, compared to English or French orthography, Arabic is probably more regular and direct in terms of vowels.