Chapter 15

Residual, Skip, and Gated Connections

Residual addition, projection shortcuts, skip connections, concatenation shortcuts, gates, identity gradient paths, and why residual blocks changed deep training.

What this chapter does

Deep networks need reliable routes for information and gradients. This chapter explains shortcut and gated paths before larger architectures hide them behind names.

Lessons

Read these in order.

Start with the chapter introduction, then move through the topic lessons. The order is chosen so each page can reuse ideas from the pages before it.

  1. 01
    Introduction

    Why deeper networks need routes for information and gradients.

  2. 02
    Residual Addition

    Residual blocks as learning a correction added to the input.

  3. 03
    Projection Shortcut

    Projecting the skip path when residual shapes are not compatible.

  4. 04
    Skip Connection

    Routing information around one or more transformations.

  5. 05
    Concatenation Shortcut

    Keeping both paths by joining features instead of adding them.

  6. 06
    Simple Gates

    Learning how much signal to pass, keep, or mix.

  7. 07
    Identity Gradient Path

    How direct paths give gradients a shorter route through deep networks.

  8. 08
    Why Residual Blocks Changed Deep Training

    Why learning small corrections made very deep networks easier to optimize.

Before moving on

  • Compute residual sums and simple gated mixtures.
  • Explain projection shortcuts and shape compatibility.
  • Compare residual addition with concatenation shortcuts.
  • Explain why identity paths help gradients in deep networks.

Where this leads

  • Numerical Precision and Stability
  • PyTorch as Compression
  • Transformers

Chapter progress