LLM Foundations

Core mechanics of large language models — training, inference, tokenization, and the mathematics of next-token prediction.

Parallel attention connections replacing sequential recurrence in transformer neural network architecture
MONA explainer 10 min

What Is Transformer Architecture and How Self-Attention Replaced Recurrence

Transformers replaced sequential recurrence with parallel self-attention. Understand QKV computation, multi-head …

Diagram of raw text splitting into subword tokens through three parallel algorithmic pathways
MONA explainer 11 min

What Is Tokenizer Architecture and How BPE, WordPiece, and Unigram Encode Text for LLMs

Tokenizer architecture determines how LLMs read text. Learn how BPE, WordPiece, and Unigram split text into subword …

Neural network projecting words into a geometric vector space with visible distance relationships between meaning clusters
MONA explainer 9 min

What Is an Embedding and How Neural Networks Encode Meaning into Vectors

Embeddings turn words into vector coordinates where distance equals meaning. Learn the geometry, training mechanics, and …

Abstract geometric visualization of attention weight matrices connecting token sequences through parallel pathways
MONA explainer 10 min

Self-Attention vs. Cross-Attention vs. Causal Masking: Attention Variants and Their Limits

Self-attention, cross-attention, and causal masking solve different problems inside transformers. Learn the math, …

Sequential chains breaking apart into parallel attention grids with quadratic scaling curves rising behind them
MONA explainer 10 min

Prerequisites for Understanding Transformers: From RNNs to Quadratic Scaling Limits

Understand why RNNs failed, how transformer self-attention trades parallelism for quadratic cost, and what these …

Geometric visualization of multi-head attention connecting tokens across transformer layers with positional encoding waves
MONA explainer 9 min

Multi-Head Attention, Positional Encoding, and the Encoder-Decoder Structure Explained

Multi-head attention, positional encoding, and encoder-decoder structure: the three mechanisms inside every transformer, …

Fractured subword fragments orbiting a merge tree with gaps revealing non-Latin script disparity
MONA explainer 10 min

Glitch Tokens, Fertility Gaps, and the Unsolved Technical Limits of Subword Tokenization

BPE tokenizers produce glitch tokens and penalize non-Latin scripts with fertility gaps. Learn where the math breaks — …

Abstract visualization of vectors in high-dimensional space with measurement rulers overlaid on a geometric grid
MONA explainer 9 min

Dense vs. Sparse, Cosine vs. Dot Product, and the Technical Limits of Vector Representations

Dense vs. sparse embeddings encode meaning differently. Learn how cosine similarity, dot product, and Euclidean distance …

Abstract geometric visualization of query key and value vectors converging through a scaled dot-product attention matrix
MONA explainer 10 min

Attention Mechanism Explained: How Queries, Keys, and Values Power Modern AI

Attention mechanisms let neural networks weigh input relevance dynamically. Learn how queries, keys, and values compute …

Geometric visualization of attention matrices expanding quadratically as sequence length grows
MONA explainer 10 min

Why Transformers Hit a Wall: Quadratic Scaling and the Memory Bottleneck

Transformer self-attention scales quadratically with sequence length. Understand the O(n²) memory wall, KV cache costs, …

Geometric matrix grid expanding quadratically with heat-map intensity fading at the edges to visualize attention cost scaling
MONA explainer 9 min

Why Standard Attention Breaks at Long Contexts: The O(n²) Bottleneck and Attention Sinks

Standard attention scales quadratically with sequence length. Learn why O(n²) breaks at long contexts, what attention …

Geometric attention matrix with query-key vectors converging across a sequence of tokens
MONA explainer 10 min

What Is the Transformer Architecture and How Self-Attention Really Works

The transformer architecture powers every major LLM. Learn how self-attention computes token relationships, why …

Abstract geometric visualization of weighted token connections flowing through a neural attention grid
MONA explainer 9 min

What Is the Attention Mechanism: Scaled Dot-Product, Self-Attention, and Cross-Attention Explained

Understand how the attention mechanism works inside transformers. Covers scaled dot-product attention, self-attention vs …

Geometric visualization of vector spaces and matrix operations underlying transformer attention mechanisms
MONA explainer 10 min

Prerequisites for Understanding Transformers: From Embeddings to Matrix Multiplication

Master the math behind transformers: embeddings, matrix multiplication, positional encoding, and multi-head attention …

Geometric visualization of vector spaces converging through dot product alignment into attention weight distributions
MONA explainer 9 min

From Embeddings to Attention: The Math You Need Before Studying Transformers

Master the math behind attention mechanisms — dot products, softmax, QKV matrices, and multi-head projections — before …