When an LLM's Inner State and Its Words Diverge: A Master Key to Understanding LLM Behavior

Using the bandwidth gap between hidden states and tokens, this article offers one explanation for LLM engineering phenomena such as Chain of Thought, prompt length, few-shot learning, personality drift, and hallucinations.

May 2, 2026 · 16 min · 3265 words · Andy SI
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The Full Landscape of LLM Training: What Every AI Application Engineer Should Understand

A systematic tour of the entire LLM training pipeline—from data pipelines, scaling laws, system constraints, synthetic data, distillation, post-training, and evaluation systems to agent training—and how these mechanisms affect model selection, evaluation, and harness design for AI application engineers.

April 4, 2026 · 32 min · 6654 words · Andy SI
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Entropy in LLMs: A Unifying Language from Training to Inference and Products

This article connects cross-entropy, perplexity, temperature, conditional entropy, hallucination detection, and prompt constraints into one line of reasoning, showing how entropy provides a unified language for understanding LLM training, inference, and product design. It also explains entropy’s practical value in RAG and engineering governance.

March 27, 2026 · 6 min · 1263 words · Andy SI
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What Is an LLM API KV Cache?

KV Cache is a key concept connecting Transformer theory with LLM engineering and deployment. Understanding it completes the path from how a model computes to how it runs.

March 5, 2026 · 17 min · 3558 words · Andy SI
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The Complete Guide to LLM Chain-of-Thought (CoT)

Understand what LLM Chain-of-Thought (CoT) is and how prompt engineering can elicit Chain-of-Thought (CoT) from an LLM.

March 4, 2026 · 12 min · 2430 words · Andy SI
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Understanding the Mathematical Intuition Behind Transformers

This article gave me—and may give you—a deeper understanding of the basic principles behind Transformers, replacing a black-box view of today’s mainstream LLMs. Cheers!

February 24, 2026 · 18 min · 3726 words · Andy SI
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