TreeOfKnowledge – Propositional & First-Order Logic Tree Engine

Author: JAnica Tesla Zrinski
Original Java symbolic logic tree engine (2002–2004)
Originally developed as a university diploma project (PMF, Zagreb)

It is designed for education, formal logic exploration, and explainable symbolic reasoning experiments.

This repository contains the core Java source code of a symbolic logic reasoning engine that builds and transforms explicit logic trees (ASTs) for:

• propositional logic
• first-order logic
• normal-form transformations

The focus is on transparent, inspectable symbolic reasoning — not black-box evaluation.

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Status: Stable legacy academic engine, preserved and modernized for educational and explainable-AI use.

Current packaged release: 1.0.0

🌳 Official website

Interactive calculators, runnable demos, and explanations:

https://TreeOfKnowledge.eu

This repository contains the core Java engine behind the calculators.
The website itself is maintained separately as a static project.

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🔬 How it works (technical overview)

TreeOfKnowledge constructs an explicit Abstract Syntax Tree (AST) for each formula.

Formulas are recursively decomposed into primitive connectives:

• ¬ NOT
• ∧ AND
• ∨ OR

Using recursive transformations and De Morgan’s laws, formulas are converted into:

• Negation Normal Form (NNF)
• Disjunctive Normal Form (DNF)
• Conjunctive Normal Form (CNF)
• minimal normal forms (where applicable)

Parsing, evaluation, and visualization follow the same recursive structure —
so every step of reasoning remains traceable and auditable.

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🎯 Core idea

The goal is not only to compute logical truth values —
but to expose step-by-step reasoning through explicit tree transformations.

Each formula becomes a concrete tree structure that can be:

• inspected
• evaluated
• transformed
• visualized

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🎓 Educational relevance

Designed as a pedagogical tool for logic and discrete mathematics.

The explicit AST representation helps learners understand:

• hierarchical formula structure
• connective precedence
• quantifier scope and nesting
• normalization procedures
• recursive evaluation

Logical reasoning becomes a visible structure, not an abstract procedure.

Suitable for:

• logic courses
• CS foundations
• recursion teaching
• symbolic reasoning demos

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🤖 Explainable AI relevance (XAI)

By exposing structure and transformation steps explicitly,
the engine illustrates principles of symbolic and explainable AI:

• visible reasoning paths
• rule-based transformations
• auditable inference structure

It serves as a minimal, fully inspectable symbolic reasoning core
that can complement modern AI systems.

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📦 Included in this repository

Core features

• formula parsing
• AST construction
• propositional logic engine
• first-order logic engine
• normalization transformations
• semantic table evaluation
• Swing GUI demo calculators

Technical properties

• pure Java
• no external frameworks
• recursive algorithms
• source-level transparency

Documentation

• LICENSE
• ORIGIN-2002.txt
• README.md

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⚙️ Requirements

• Java 8 or newer

Tested with:

• Java 21 (Temurin)
• IntelliJ IDEA
• VS Code
• standard Java CLI tools

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▶ Running

Quick start (CLI)

javac propositional/*.java
java propositional.Calc

Compile sources and run a calculator launcher class.

Or run directly from an IDE by launching the desired Calc class.

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🏫 Origin note

The core algorithms originate from academic work developed
during a university diploma project at PMF Zagreb (2002–2004).

This repository preserves and modernizes that original logic tree engine.

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📬 Contact

For academic collaboration, educational use, or licensing inquiries —
please contact the author.