books.google.co.uk - The central contention of this book is that second-order logic has a central role to play in laying the foundations of mathematics. In order to develop the argument fully, the author presents a detailed development of higher-order logic, including a comprehensive discussion of its semantics. Professor...http://books.google.co.uk/books/about/Foundations_without_Foundationalism_A_Ca.html?id=xm5eWgjpYU0C&q=set+of+formulas&utm_source=gb-gplus-shareFoundations without Foundationalism : A Case for Second-Order Logic
