Does 'a[i] = i;' always result in well defined behaviour?

Question

There are several interesting questions raised here regarding undefined behaviour in C. One of them is (slightly modified)

Does the following piece of code r

Answer 1

No it doesn't. The first line has a sequence point (the comma), so it is not undefined behaviour:

int i = 0, *a = &i;

The second line is perfectly normal.

a[i] = i + 1;

Since i + 1 creates a temporary value, i gets modified only once, on the assignment. This however would be undefined behaviour:

a[i] = i++;