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ENGINEERING JOURNAL

WHAT I LEARNED FROM MY STUPID STUFF

I built something. I broke something. I learned something. Here is the evidence. Read this so you don't have to suffer the way I did.

THE MANIFESTO • LESSONS & EVIDENCE

WHAT I LEARNED FROM MY STUPID STUFF

I built something. I broke something. I learned something.

Here is the evidence.

Read this so you don't have to suffer the way I did.

01. SYSTEMS & KERNELS

Sockets, concurrency, memory allocators, compilers, and OS boundaries.

02. AI & ML MECHANICS

Attention, tokenization, quantization, KV caching, and edge inference.

03. ARCHITECTURE & TRADE-OFFS

Analyzing performance, latency, microservices vs monoliths, and building to understand.

RABBIT HOLE:
SHOWING 41 OF 41 ARTICLES
Engineering2026-08-31

A Larger Context Window Does Not Remove the Need for RAG

A large context window sounds like it should make retrieval unnecessary. But after working with constrained local models and explicit retrieval pipelines, I started looking at the problem differently: context capacity and context quality are two different engineering problems.

#AI#RAG#LLM
QV
Quan Van
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Artificial Intelligence2026-08-31

Why Does Segmentation Need Multiple Scales?

I started looking at segmentation architectures from a different angle: the real problem is not simply predicting a class for every pixel, but preserving enough spatial information while building representations with a sufficiently large receptive field.

#AI#Computer Vision#Image Segmentation
QV
Quan Van
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Artificial Intelligence2026-08-23

What Actually Happens Inside an Image Segmentation Model?

An image segmentation model does not simply 'recognize objects'. Mathematically, it transforms a tensor of pixels through a sequence of learned functions and produces a probability distribution for every pixel. This article derives the mathematics behind that process.

#AI#Computer Vision#Image Segmentation
QV
Quan Van
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Software Engineering2026-08-23

BLOG: What Actually Happens When You Call a Framework API?

We use frameworks every day, but how much of their internal machinery do we actually understand? Let's go underneath the API and trace what really happens when a framework processes a request.

#Framework#Backend#Architecture
QV
Quan Van
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Artificial Intelligence2026-08-23

What If AI Never Learned Anything? Can Pure Mathematics Build an Intelligent System?

Before neural networks dominated AI, intelligent behavior was already being built from logic, probability, search, optimization, graphs, and mathematical models. But if we completely remove training and build an AI system using only mathematics, what can it actually solve—and where does it fundamentally break?

#AI#Artificial Intelligence#Mathematics
QV
Quan Van
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Backend Engineering2026-08-23

Why Can Adding an Index Make Your Database Slower?

Indexes make database reads faster—or at least that's what we usually learn. But in production systems, adding an index can actually make writes slower, increase storage pressure, and sometimes even cause the optimizer to choose a worse execution plan.

#Database#PostgreSQL#MySQL
QV
Quan Van
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Technology2026-08-23

BLOG: Why Does Adding More CPU Sometimes Make a Backend Slower?

A senior-level deep dive into concurrency, contention, queueing, lock amplification, and why throwing more CPU at a backend can sometimes make the system slower.

#Backend Engineering#Performance Engineering#Concurrency
QV
Quan Van
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Backend Engineering2026-08-23

BLOG: Why Adding More Threads Can Make Your Backend Slower

A deep dive into concurrency, contention, context switching, queueing, and why increasing the number of workers doesn't necessarily increase throughput.

#Concurrency#Backend#Performance
QV
Quan Van
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Artificial Intelligence2026-08-23

BLOG: Why Does RAG Sometimes Make an LLM Worse?

RAG is often presented as the obvious solution to hallucination. But retrieval can also make an LLM less accurate, less confident, and sometimes completely wrong. Let's understand why.

#AI#LLM#RAG
QV
Quan Van
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Engineering2026-08-22

Beyond the Abstraction: Notes on Technology, Engineering, and Everything In Between

A personal manifesto and space for exploring technology, systems, AI mechanics, and the ideas that sit beneath the abstractions we use every day.

#Technology#Software Engineering#Systems
QV
Quan Van
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Computer Science2026-08-22

What Actually Happens Inside a Database Query? From SQL to the Execution Plan

A deeper investigation into how a relational database transforms SQL into an executable plan, covering parsing, binding, optimization, cardinality estimation, index selection, physical operators, and execution.

#Databases#SQL#Query Optimizer
QV
Quan Van
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Software Engineering2026-08-22

What Actually Happens Inside an ORM? From Model Definition to SQL Execution

A technical investigation into what really happens between an ORM query and the database, exploring model metadata, query construction, parameter binding, SQL generation, execution, and result hydration.

#ORM#Database#Backend
QV
Quan Van
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Software Engineering2026-08-22

What Actually Happens Inside a React Render? From State Update to DOM Commit

A technical investigation into the internal lifecycle of a React update, from state mutation and Fiber scheduling to reconciliation and the final commit into the DOM.

#React#Frontend#JavaScript
QV
Quan Van
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Computer Systems2026-08-22

What Actually Happens When You Type a URL Into a Browser?

A systems-level investigation into the chain of events triggered by a URL: parsing, DNS resolution, connection establishment, TLS negotiation, HTTP, and browser rendering.

#Web#Networking#HTTP
QV
Quan Van
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Computer Science2026-08-22

Why Databases Use B-Trees: The Mathematics Behind Efficient Disk-Based Search

A technical investigation into why database indexes rely on B-Trees and B+Trees, and how high fan-out transforms disk-based search from an expensive linear process into logarithmic traversal.

#Databases#B-Trees#B+Trees
QV
Quan Van
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Engineering Blog2026-07-18

Distributed Data Integrity: Patterns for Microservices Architecture

A technical deep dive into maintaining data integrity across microservices, exploring Distributed Transactions, the Saga pattern, Transactional Outbox, and the shift toward Eventual Consistency.

#Microservices#System Design#Distributed Systems
QV
Quan Van
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Engineering Blog2026-07-18

Next.js Evolution: The Paradigm Shift from Pages Router to App Router

An architectural analysis of the monumental shift from the legacy Pages Router to the modern App Router in Next.js, highlighting RSCs, routing conventions, and data fetching paradigms.

#Next.js#App Router#React Server Components
QV
Quan Van
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Engineering Blog2026-07-18

Demystifying Next.js Hydration and the 'Hydration Mismatch' Error

An in-depth look into the mechanics of Next.js Hydration, why the infamous 'Hydration Mismatch' error occurs, and the standard engineering practices to resolve it.

#Next.js#React#Frontend
QV
Quan Van
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Engineering Blog2026-07-18

Next.js App Router: The Architectural Divide Between Server and Client Components

An architectural breakdown of React Server Components (RSC) in the Next.js App Router, exploring the strict divide between Server and Client execution environments.

#Next.js#React#Server Components
QV
Quan Van
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Engineering Blog2026-07-18

React Lifecycle Mechanics: Mapping Component Synchronization to useEffect

A deep dive into the React component lifecycle, exploring the mental shift from class-based lifecycle methods to functional synchronization using the useEffect hook.

#React#Hooks#Frontend
QV
Quan Van
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Engineering Blog2026-07-18

State Management in React: Local, Global, and the Server State Paradigm

A comprehensive guide to drawing boundaries between Local, Global, and Server State in modern React, featuring tools like Zustand, Redux Toolkit, and TanStack Query.

#React#State Management#Frontend
QV
Quan Van
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Engineering Blog2026-07-18

Demystifying Rendering: Server-Side (SSR) vs. Client-Side (CSR) in Next.js

A comprehensive breakdown of Server-Side Rendering (SSR) and Client-Side Rendering (CSR), their architectural trade-offs, and how to choose the right pattern for your Next.js applications.

#Next.js#SSR#CSR
QV
Quan Van
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Scientific Research2026-04-10

Autoregressive Masking: Formalizing the Causal Mask in Transformer Decoder Architectures

A technical analysis of the Causal Mask, the structural constraint that enforces autoregressive generation in Decoder-only Transformers. This paper derives the mechanism's mathematical basis and its role in preventing attention leakage across future tokens.

#Transformers#Attention#Deep Learning
QV
Quan Van
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Scientific Research2026-04-10

Inverse Diffusion and Latent Manifolds: Formalizing Generative Mechanics in AI Synthesis

An investigation into the mathematical foundations of Generative AI, focusing on Inverse Diffusion processes and Latent Space formalization for image and text synthesis.

#Generative AI#Diffusion Models#GANs
QV
Quan Van
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Scientific Research2026-04-10

Multi-Head Attention: The Engine of Parallel Representation in Transformers

A comprehensive breakdown of Multi-Head Attention, the mathematical framework that allows Transformers to capture parallel semantic subspaces simultaneously.

#Transformers#Attention#Deep Learning
QV
Quan Van
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Scientific Research2026-04-10

Understanding the Context Window: The Short-Term Memory of LLMs

An exploration of the context window in Large Language Models, detailing its token-based architecture, O(N^2) computational complexity, and the 'Lost in the Middle' phenomenon.

#LLM#Context Window#Deep Learning
QV
Quan Van
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Scientific Research2026-04-10

Scaling in Transformer Architectures: The Mathematical Rationale behind $\sqrt{d_k}$

A derivation of the variance explosion in high-dimensional dot products and its deleterious effects on softmax saturation and gradient propagation.

#Transformer#Attention#Deep Learning
QV
Quan Van
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Scientific Research2026-04-09

Statistical Tokenization: Formalizing the Byte Pair Encoding (BPE) Algorithm for Subword Decomposition

A technical investigation into Byte Pair Encoding (BPE), the subword tokenization standard for Large Language Models. This paper details the iterative transition from character-level granularity to high-density subword dictionaries.

#NLP#Tokenization#LLM
QV
Quan Van
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Scientific Research2026-04-09

Attention Dynamics: Formalizing Scaled Dot-Product Mechanisms in Transformer Architectures

A technical formalization of the Scaled Dot-Product Attention mechanism. This paper analyzes the topological interaction between Queries, Keys, and Values, providing a step-by-step numerical derivation of the attention pipeline.

#Transformers#Self-Attention#Deep Learning
QV
Quan Van
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Scientific Research2026-04-09

Synthesizing Minority Samples: A Formal Analysis of Linear Interpolation in Imbalanced Classification

A rigorous mathematical investigation into the Synthetic Minority Over-sampling Technique (SMOTE). This paper details the k-NN selection process and the geometric foundations of linear interpolation used to expand decision boundaries in imbalanced datasets.

#Machine Learning#Data Science#Imbalanced Learning
QV
Quan Van
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Scientific Research2026-04-09

Strategic Informatics: A Formal Investigation into Undersampling Mechanisms for Imbalanced Classification

A technical exploration of majority class reduction strategies. This paper formalizes Random Undersampling, the NearMiss heuristic suite, and Tomek Link boundary cleaning for optimizing inference in high-imbalance network traffic datasets.

#Machine Learning#Data Science#Imbalanced Learning
QV
Quan Van
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Scientific Research2026-04-08

Automata as Memory: Decoding LSTM State Persistence in Terminal Sequences

A rigorous mathematical analysis of the divergence between Cell State ($C_L$) and Hidden State ($h_L$) at the terminal step of Long Short-Term Memory architectures. Explores the functional roles of these states in Many-to-One and Many-to-Many topologies.

#Deep Learning#LSTM#Architecture
QV
Quan Van
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Scientific Research2026-04-08

Embedding Vector vs Standard Vector: The Mathematical Soul of Modern AI

A comparative study between engineered standard vectors and learned embedding vectors, exploring latent feature spaces and semantic arithmetic in Deep Learning.

#AI#Vector#Embedding
QV
Quan Van
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Scientific Research2026-04-08

The Calculus of Compression: Mathematical Foundations of Post-Training Quantization (PTQ)

A formal exploration of affine quantization mapping. This paper details the derivation of scaling factors and zero-points for converting FP32 tensors to INT8 precision while preserving structural fidelity during inference.

#Model Compression#Quantization#Inference
QV
Quan Van
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Scientific Research2026-04-08

Foundations of Recurrent Architectures: Parameter Sharing and Temporal Dynamics

An analytical study of Recurrent Neural Networks (RNNs), examining the mathematical mechanics of parameter sharing, temporal hidden states, and the vanishing gradient bottleneck.

#Deep Learning#RNN#Mathematics
QV
Quan Van
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Scientific Research2026-04-07

LoRA vs QLoRA: The Ultimate Memory Bottleneck Showdown

A deep dive comparing LoRA and QLoRA, analyzing their mathematical mechanics, memory constraints, and how they democratize LLM fine-tuning.

#LLM#Fine-Tuning#LoRA
QV
Quan Van
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Scientific Research2026-04-07

Mathematical Foundations of Spatial and Temporal Subsampling: A Study on Pooling Layers

A rigorous mathematical analysis of dimensionality reduction in Deep Learning, exploring the formal mechanics of Max, Average, and Global Pooling across 1D, 2D, and 3D architectures.

#Deep Learning#CNN#Mathematics
QV
Quan Van
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Scientific Research2026-04-07

Taxonomy of Machine Learning Optimization: A Survey of Training Paradigms

A systematic categorization of algorithmic training methodologies in Artificial Intelligence, analyzing the mathematical foundations of Supervised, Unsupervised, and Reinforcement Learning.

#Machine Learning#Deep Learning#Training Paradigms
QV
Quan Van
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Scientific Research2026-04-06

Mathematical Foundations of Convolutional Architectures: A Spatiotemporal Research Study

A rigorous mathematical exploration of convolutional operations in 1D, 2D, and 3D spaces. Analyzing receptive field dynamics, computational complexity, and dimensionality mapping in deep neural networks.

#Deep Learning#Mathematics#CNN
QV
Quan Van
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Scientific Research2026-04-06

Distributed Data Parallel (DDP) Architecture: Mathematical Foundations of Ring All-Reduce

A rigorous mathematical and architectural analysis of Distributed Data Parallel (DDP) in PyTorch. Explores the GIL bottlenecks of legacy systems and the efficiency of the Multi-process Ring All-Reduce topology.

#Deep Learning#DDP#Architecture
QV
Quan Van
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Scientific Research2026-04-05

Computational Efficiency in Edge AI: Optimization via Pythonic Lazy Evaluation

An analysis of memory management strategies for resource-constrained Edge AI devices, focusing on the mechanics of Python Generators and the 'yield' primitive.

#Python#Memory Optimization#Edge AI
QV
Quan Van
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