In mathematics, a weak Lie algebra bundle ξ = {\displaystyle \xi =\,} is a vector bundle ξ {\displaystyle \xi \,} over a base space X together with a morphism θ : ξ ⊗ ξ → ξ {\displaystyle \theta :\xi \otimes \xi \rightarrow \xi } which induces a Lie algebra structure on each fibre ξ x {\displaystyle \xi _{x}\,}. Wikipedia