Terminology 38: An inference is an act or process of knowing a claim to be the case. We make inferences in a context of statements, called assumptions. The context starts empty. At any time we may add a statement to the context by saying we assume it. We express the inference that a statement \phi holds by \vdash \phi or, in practice, by simply stating \phi assertively. If we may infer, with \phi in the context, that a statement \psi holds, then we may infer in the context obtained by removing \phi that \phi entails \psi , denoted \phi \vdash \psi.