The theoretical essence of the principle of equivalence is not to cheat patents. This theory comes from Winans v. Denmead in the United States, "in order to reduce strict logic and prevent infringers from stealing other people's invention income." The basic idea of the principle of equivalence is that in patent infringement litigation, a technology suspected of infringement, compared with patented technology, although not literally within the scope of patent claims, has substantially the same function (way) and obtains substantially the same result (result). According to this judgment standard, it can be regarded as constituting patented technology.
The theoretical basis of this principle is that "if two inventions use essentially the same method, handle the same work and produce the same result, then they are the same, although they are different in name, form or shape."
I don't know what your second question means.