  Derived equivalences for Artin algebras (and almost $\nu$-stable derived
equivalences for finite-dimensional algebras) are constructed from Milnor
squares of algebras. Particularly, three operations of gluing vertices,
unifying arrows and identifying socle elements on derived equivalent algebras
are presented to produce new derived equivalences of the resulting algebras
from the given ones. As a byproduct, we construct a series of derived
equivalences, showing that derived equivalences may change Frobenius type of
algebras in general, though both tilting procedure and almost $\nu$-stable
derived equivalences do preserve Frobenius type of algebras.
