ICHD classification and diagnosis of migraine are further subdivided. Overall ICHD-3 beta distinguishes 29 migraine subtypes. The following table outlines the main subtypes and their ICHD-1, -2, -3 beta and ICD-10 codes. Migraine without aura also referred to as a "common migraine", (previously known as "hemicrania simplex") is a specific neurological disorder characterized by recurrent, throbbing headaches that often affect one side of the head (i.e., it is unilateral), are of at least moderate intensity, and may cause nausea, phonophobia or photophobia. One defining characteristic of the common migraine is a lack of the visual disturbances known as an aura. The exact International Classification of Headache
Formally étale morphism Formally étale morphism In commutative algebra and algebraic geometry, a morphism is called formally étale if it has a lifting property that is analogous to being a local diffeomorphism. Let "A" be a topological ring, and let "B" be a topological "A"-algebra. "B" is formally étale if for all discrete "A"-algebras "C", all nilpotent ideals "J" of "C", and all continuous "A"-homomorphisms , there exists a unique continuous "A"-algebra map such that , where is the canonical projection. Formally étale is equivalent to formally smooth plus formally unramified. Since the structure sheaf of a scheme naturally carries only the discrete