Sir Isaac Newton's philosophi Naturalis Principia Mathematica'(the
Principia) contains a prose-style mixture of geometric and limit
reasoning that has often been viewed as logically vague.
In A Combination of Geometry Theorem Proving and Nonstandard
Analysis, Jacques Fleuriot presents a formalization of Lemmas and
Propositions from the Principia using a combination of methods from
geometry and nonstandard analysis. The mechanization of the procedures,
which respects much of Newton's original reasoning, is developed within
the theorem prover Isabelle. The application of this framework to the
mechanization of elementary real analysis using nonstandard techniques
is also discussed.