natural+man
131Natural rubber — Rubber and India rubber redirect here. For other uses, see Rubber (disambiguation). This article is about the polymeric material natural rubber. For man made rubber materials, see Synthetic rubber. Latex being collected from a tapped rubber tree …
132Natural deduction — In logic and proof theory, natural deduction is a kind of proof calculus in which logical reasoning is expressed by inference rules closely related to the natural way of reasoning. This contrasts with the axiomatic systems which instead use… …
