# General schemes

Arbitrary schemes over a commutative base ring $\mathbb k$ with unit are instances of the abstract type

SchemeType
Scheme{BaseRingType<:Ring}

A scheme over a ring $𝕜$ of type BaseRingType.

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Morphisms of schemes shall be derived from the abstract type

SchemeMorType
SchemeMor{DomainType, CodomainType, MorphismType, BaseMorType}

A morphism of schemes $f : X → Y$ of type MorphismType with $X$ of type DomainType and $Y$ of type CodomainType.

When $X$ and $Y$ are defined over schemes $BX$ and $BY$ other than $Spec(𝕜)$, BaseMorType is the type of the underlying morphism $BX → BY$; otherwise, it can be set to Nothing.

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