# Phase 3: Deep Learning Core

> Neural networks from first principles. No frameworks until you build one yourself.

## Start this phase on GitHub

**Prerequisites:** Phase 1 Linear Algebra Intuition. Phase 2 is recommended
for model evaluation vocabulary.

**First lesson:** [The Perceptron](01-the-perceptron/)

Run this command from the repository root:

```bash
python3 phases/03-deep-learning-core/01-the-perceptron/code/perceptron.py
```

Keep the command, exit code, converged gate results, XOR failure of a single
perceptron, and the final two-layer XOR predictions.

**Next action:** Explain why one linear boundary cannot solve XOR, then
continue to [Multi-Layer Networks and Forward Pass](02-multi-layer-networks/).

Browse the [full Phase 3 lesson list](../../README.md#phase-3) or the
[cross-phase roadmap](../../ROADMAP.md).