(Parts I, II) “The 2456th Century was matter-oriented, as most Centuries were, so he had a right to expect a basic compatibility from the very beginning. It would have none of the utter confusion (for anyone born matter-oriented) of the energy vortices of the 300s, or the field dynamics of the 600s.” (Isaac Asimov, The…
The computational content of Nonstandard Analysis
We discuss the computational content of Nonstandard Analysis based on recent proof-theoretic developments.
A new linear inference of size 8
Linear inferences are propositional tautologies of the form , where and are formulas with at most one occurrence of each propositional variable. These form a -complete set, but surprisingly little is known about their structure, despite their importance in structural proof theory (and beyond). In this post I will cover some of the background on…
What proof mining is about, Part II: Structures and metatheorems
As I said last time, it is time to raise the stakes and start dealing with sentences involving structures, which at first will be the structures of first-order logic. Let, then, be a first-order signature and be a family of -sentences. For the purposes of this post, we shall say, for any -structure , that…
