Verish

Verish is a language for reasoning that resembles a natural language. It is equivalent to Lower Predicate Calculus, and has a built-in framework for defining and using abbreviations, and for introducing additional principles of reasoning that can be automatically expanded into a sequence of steps that use only basic principles of reasoning. It has a basic reasoning checking function, and can automatically expand one additional principle of reasoning into a sequence of steps using only the basic principles. It can also add HTML markup to a proof for display as a Web page.