### Every Pointfree Funcoid on a Semilattice is an Algebraic Structure

Continuing this blog post: The set of all pointfree funcoids on upper semilattices with least elements is exactly a certain algebraic structure defined by propositional formulas. Really just add the identities defining a pointfree funcoid to the identities of an upper semilattice…

### Funcoid is a “Structure” in the Sense of Math Logic

A few seconds ago I realized that certain cases of pointfree funcoids can be described as a structure in the sense of mathematical logic, that is as a finite set of operations and relational symbols. Precisely, if a pointfree funcoid \$latex f\$…

### My old files related with math logic

In 2005 year I put online some math articles related with formulas and math logic (despite I am not a professional logician). In 2005 I like a crackpot thought that I discovered a completely new math method replacing axiomatic method. This was…

### How proof by contradiction differs of direct proof

This my post is about mathematical logic, but first I will explain the story about people who asked or answer this question. A famous mathematician Timoty Gowers asked this question: What is the difference between direct proofs and proofs by contradiction. We,…