Definition 78.15.1. Let $S$ be a scheme. Let $B$ be an algebraic space over $S$ Let $(U, R, s, t, c)$ be a groupoid in algebraic spaces over $B$. Let $u \in |U|$ be a point.

We say $R$ is

*strongly split over $u$*if there exists an open subspace $P \subset R$ such that$(U, P, s|_ P, t|_ P, c|_{P \times _{s, U, t} P})$ is a groupoid in algebraic spaces over $B$,

$s|_ P$, $t|_ P$ are finite, and

$\{ r \in |R| : s(r) = u, t(r) = u\} \subset |P|$.

The choice of such a $P$ will be called a

*strong splitting of $R$ over $u$*.We say $R$ is

*split over $u$*if there exists an open subspace $P \subset R$ such that$(U, P, s|_ P, t|_ P, c|_{P \times _{s, U, t} P})$ is a groupoid in algebraic spaces over $B$,

$s|_ P$, $t|_ P$ are finite, and

$\{ g \in |G| : g\text{ maps to }u\} \subset |P|$ where $G \to U$ is the stabilizer.

The choice of such a $P$ will be called a

*splitting of $R$ over $u$*.We say $R$ is

*quasi-split over $u$*if there exists an open subspace $P \subset R$ such that$(U, P, s|_ P, t|_ P, c|_{P \times _{s, U, t} P})$ is a groupoid in algebraic spaces over $B$,

$s|_ P$, $t|_ P$ are finite, and

$e(u) \in |P|$

^{1}.

The choice of such a $P$ will be called a

*quasi-splitting of $R$ over $u$*.

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