Author(s): Saif Ali Kheraj

Originally published on Towards AI.

https://arxiv.org/pdf/2106.09685

In the era of large language models, Transformer is like the original brain of AI. But they come with a catch: Full fine tuning them is like …. Enter LoRA (Low-Rank Adaptation) — “Hey, what if we only train the parts we really need?”

Think of LoRA as adding a tiny steering wheel to a giant spaceship. You don’t need to rebuild the engine to change direction, just bolt on a little adapter. In this article, we’ll dive into the math , explain how LoRA works under the hood, and show where it fits in the Transformer architecture.

Let’s say you have a neural network layer with:

Input size: d = 10Output size: k = 8

The number of parameters in the weight matrix W0 is 10 x 8 which is 80 . That’s fine for small models. But with models like GPT or BERT, we’re talking millions of parameters — and training all of them is expensive, both in time and in your GPU’s emotional well-being.

So LoRA says: “Freeze the big guy, train a tiny plug in instead.”

Normally, a neural layer does:

Figure by Author

Now LoRA adds twist.

Figure by Author

But instead of making delta W, a full-sized matrix (which would defeat the purpose), we… Read the full blog for free on Medium.

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Published via Towards AI