At the beginning of August, there is LTC halving. Does Btc and ltc move together or does ltc increase independently?
I still do not feel any frenzy about the Litecoin halving and its looking a bit dissimilar to what it was the past time. Or maybe it's too early to judge. Secondly, both btc and ltc are quite independent despite the fact that ltc traces back to btc but then it's still an altcoin
Too early to judge, in my opinion. Although past performance does nor equate to a success in the future, but judging from its past halving, LTC did quite good, to be honest. Other's have said that LTC is going to die, guinea pig for its big brother BTC, but so far it is holding on its own. So personally, I think something big will happen after the halving and it might go near or even top its previous all-time-high.
Litecoin is not dying that easily simply because it is a very old coin that has succeeded this long and more importantly because it has a couple of good developers who are working on it hard.
but also it is not dying because other altcoins are practically just as useless as LTC without that much to offer so there is no alternative to replace it with.