• Intuitionistic Logic +

Intuitionistic logic extended with the assumption that some symbols are decidable (classical) combines classical and intuitionistic features.

• Beyond Constant Propagation

Traditional data flow analysis can be extended to collect information and reason about program expressions. This enhanced analysis is executed by a fixpoint algorithm that incorporates a rule-based inference procedure.

• Constraint Functional Logic Programming Before It Was So Named

Specification of programs in functional notation combined with relational constraints. Programs derivation using logical rules.

• Logics for Artificial Intelligence
Logical characterization of AI systems. These logics include nonlogical axioms expressing domain knowledge.

• Fuzzy and Neural-Symbolic Computing
Neural-symbolic computing studies methods combining symbolic reasoning and neural networks. Fuzzy computing estimates the degree of truth of logical statements in the environments where truth values belong to a continuous interval.

• Subsets of Context-Free Languages and Their Automata
One-counter automata, input-driven languages, stochastic automata, etc.

Math undoubtedly stands out from other disciplines due to its exclusive spiritual nature. Here are some math pearls substantiating the above statement, and I am especially delighted with them:

The Church-Turing thesis     G�del's Incompleteness Theorems     Recursively Undecidable     Cantor's Diagonal Method

All these links lead to Eric Weisstein's World of Mathematics. It is an excellent online mathematical encyclopedia - the best I know of so far - hosted by Wolfram Research. See my own contributions to this encyclopedia:

Axiom Schema     Birkhoff's Theorem     Church-Rosser Property     Church-Rosser Theorem     Confluence     Creative Set     Critical Pair     Cut Elimination     Equational Logic     Finitely Terminating     First-Order Predicate Calculus     Formal Language     General Recursive Function     Godel Number     Grammar     Ground Atom     Ground Clause     Ground Literal     Herbrand Base     Herbrand's Theorem     Herbrand Universe     Horn Clause     Interpretation     Intuitionistic Logic     Kleene's Recursion Theorem     Kleene's s-m-n Theorem     Knuth-Bendix Completion Algorithm     Konig's Lemma     Loewenheim-Skolem Theorem     Modus Ponens     Partial Evaluation     Prenex Normal Form     Productive Set     Propositional Calculus     Recursively Isomorphic     Recursive Set     Recursively Enumerable Set     Recursively Undecidable     Reducible     Reduction Order     Reduction System     Regular Expression     Resolution     Resolution Principle     Rice's Theorem     Sequent Calculus     Skolem Function     Skolem Standard Form     Strict Order     Term Rewriting System     Unification     Universal Algebra
 

Check out the ultimate guide to Foundations of Mathematics It is my collection of links to quality materials on the subject. Some principal researches in this area contributed to the creation of this guide as well - see acknowledgement on that page. This guide is organized as a book contents page and intended to be a reference for studying foundations of mathematics. My other reference materials devoted to mathematical logic are: a comprehensive collection of Logical Laws     Sequent Calculus Primer with multiple derivation examples

Also, Tim's Triangular Page contains necessary information about triangles for school students.

Visit the web site of St. Petersburg Mathematical Society of which I am a member.