Galois Correspondence

A bijective, order-reversing correspondence between intermediate fields of a finite Galois extension and subgroups of its Galois group, realized by mapping a subgroup to its fixed field and an intermediate field to the subgroup of automorphisms that fix it.

A bijective (order-reversing) correspondence between intermediate substructures of a field extension and subgroups of the extension's automorphism group, which identifies subfields fixed by subgroups with the subgroups themselves in the case of a Galois extension.