Formal logic is cool because it can be applied not just to technical topics like mathematics or programming, but really any topic where "reasoning" is involved. Typically, a basic course in logic will teach you about propositional logic as a basis, and then move on to predicate logic as a more powerful tool. But in between those two forms of logic exists a third in terms of expressivity: modal logic, which allows talking about the *ways* in which statements might be true or false. This makes modal logic useful to analyze individual programs or distributed systems, but also fun stuff like board game strategies. And because modal logic is still simpler than predicate logic, it is easier to work with and in many cases even allows for algorithmic checking - which also powers formal verification tools like TLA+ and Alloy.

This talk should be accessible for those without any background in formal logic - I will go over the basics before diving deeper into modal logic. All you'll need is some familiarity with programming and a willingness to look at weird maths symbols. :>