Here I've edited the definition of formal system to be a little more idiomatic, though I'm not sure how you'd want to handle the formatting (italics vs bold for defined terms).
Also, this is the first section of the first chapter -- jumping right into a definition can be a little intimidating. :) I thought a short intro paragraph would be helpful here, but feel free to change it or throw it out.
Here I've edited the definition of formal system to be a little more idiomatic, though I'm not sure how you'd want to handle the formatting (italics vs bold for defined terms).
Also, this is the first section of the first chapter -- jumping right into a definition can be a little intimidating. :) I thought a short intro paragraph would be helpful here, but feel free to change it or throw it out.