The universal property of the tensor product states that for linear spaces U,V,W over a field P, if there exists a bilinear map φ:U×V→W such that for any bilinear map f:U×V→P (where P is an arbitrary linear space over P), there exists a unique linear map τ:W→P making the diagram commute (i.e., f=τφ), then the pair (W,φ) is called a tensor product of U and V.
Conditions: U,V,W are linear spaces over the field P.; φ is a bilinear map from U×V to W.; f is a bilinear map from U×V to an arbitrary linear space P over P.; τ is the unique linear map from W to P.