Sparsity is a measured way of optimizing machine learning models by deliberately specifying which nodes are composed of zero values.
Sparse models, as opposed to dense models, contain mostly zero values. This is different to models which have missing values, because in the case of a sparse model the zero values are known, but contain no numerical values.
This factor may sound irrelevant, but it is important when trying to optimize neural network processing. By specifically identifying zero values in a network, less computational effort can be directed at those values, which makes the performance of the whole network faster and more efficient.
The AI optimization game
A good analogy would be to imagine playing a game of Jenga, which involves removing blocks from a stacked tower of other blocks.
The challenge is to remove each piece without collapsing the tower. In the same way a sparse model is an AI neural network which has metaphorically removed the unnecessary elements (i.e. zero values) but still managed to maintain the integrity of the whole network.
The ‘tower’ or model doesn’t collapse without these elements. The objective is to make the AI system less resource-intensive, without sacrificing its ability to perform complex tasks.
This kind of component and resource optimisation is becoming increasingly essential as AI networks grow in size and complexity.
Neural networks now contain billions of intricate web-like nodes, composed of numerical values, many of which are zero. By identifying and removing these redundant elements, the model can compute its responses and output much quicker and more efficiently.
Sparse versus dense
The contrast with dense models is that in a dense model every neuron is connected to every other neuron in adjacent layers, and the dense array contains mostly non-zeros.
This allows for more complex computation, at the expense of increased resource requirements and slower performance.
It’s important to remember that not all parameters in a modern AI model are of equal importance. Sparsity allows AI engineers to ignore the less valuable ones in their designs, without impacting the performance of the model as a whole.
The concept of sparsity shot to prominence with the recent launch of the DeepSeek model. The folks who designed this open source model achieved their outstanding performance on modest hardware through the clever use of sparsity in the design.
By employing their in-house developed Native Sparse Attention mechanism, which selectively and dynamically deactivates non-essential components of the neural network, the team were able to reduce total compute requirements by 40-60% compared to traditional dense transformers.
This in turn led to cost efficiencies of around 10-15% of GPT-4’s operational costs with comparable performance. This form of conditional computation, where only 30–40% of the neural network is activated for any given task, also results in significant memory bandwidth savings, estimated at a 3x reduction in VRAM usage.
Bringing AI to the rest of us
The other important feature about sparsity in neural networks, is the fact that it allows AI to run on low-power computational devices such as phones, home computers or other devices.
This is especially important in the field of portable tools such as remote healthcare or education, where the lack of internet connection would otherwise hamper the deployment of valuable AI systems.
The arrival of DeepSeek, and other efficient open-source AI models, has demonstrated the feasibility and value in optimizing AI design and operation as much as possible. Sparsity is just one of a growing number of methodologies which will inevitably radically transform the AI environment over the coming years.
While dense models will continue to dominate the landscape for applications which require high levels of performance and complexity, sparse models are destined to deliver value at the cutting edge of optimized AI needs.
