V ( R ) \mathcal {V}(R) denotes the category of algebraic vector bundles on P R 1 , R {\mathbf {P}}_R^1,\;R a commutative, noetherian ring. If K K is a field, it is known that any F ∈ V ( K ) \mathcal {F} \in \mathcal {V}(K) is isomorphic to a (unique) direct sum of line bundles. If p ∈ Spec R \mathfrak {p} \in \operatorname {Spec} R and K ( p ) K(\mathfrak {p}) is the quotient field of R / p R/\mathfrak {p} , any F ∈ V ( R ) \mathcal {F} \in \mathcal {V}(R) induces a bundle in V ( K ( p ) ) \mathcal {V}(K(\mathfrak {p})) , and so a decomposition into line bundles. If the decomposition is the same for each p , F \mathfrak {p},\;\mathcal {F} is said to be uniform. It is shown that if R R is reduced, uniform vector bundles on P R 1 {\mathbf {P}}_R^1 are sums of tensor products of (pullbacks of) bundles on Spec R \operatorname {Spec} R with line bundles on P R 1 {\mathbf {P}}_R^1 .
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