I’m looking for an explanation of when to use the following conjunctions. How can I decide which is appropriate for a given sentence? Are there also strict grammatical rules that determine when each should be used?
1) “tale da” vs “a tale punto da” (two sentence clauses with the same subject)
2) “tale che” vs “a tal punto che” (two sentence clauses with different subjects)
3)”così tanto da” vs “così tanto che”
1) and 2)
First it's very common use the truncated form before a consonant if you use "A tal punto"
Anyway A tal punto da / a tal punto che have the same meaning of tale da / tale che except that they assume there's an imaginary point to be reached and reaching that point cause consequences. It's almost strengthen what you mean. But it's very hard tell when you have to use one or the other way: sometimes you can use both, sometimes you can't.
Talking by (funny) example
La casa è rossa a tal punto che sembra una fragola
The house is so red that seems a strawberry
but it sounds bad saying
La casa è rossa tale che sembra una fragola
The house is so red that seems a strawberry
Using "a tal punto" means that the house is so red which looks almost like a strawberry: if it wasn't so red, it'd look like a house.
3)
In "Così tanto che/da" but also in the 1) and 2) examples che and da are proposition consecutive and introduce subordinate clauses. Che uses verbs conjugated to the subject. Da uses infinitive verbs.
La casa è rossa a tal punto che sembra una fragola
La casa è rossa a tal punto da sembrare una fragola
Hope this helps you.. But I'm not an italian teacher
