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Gen AI Cheat Sheet

Quick reference guide for prompt engineering, sampling hyperparameters, Transformer math, RAG architecture, and fine-tuning.

Last updated: 2026-07-25

Sampling Hyperparameters

Command / PatternDescription
Temperature (T = 0.0 – 0.2)

Deterministic, greedy decoding. Best for code, math, factual extraction, and JSON schema formatting.

Temperature (T = 0.7 – 1.0)

Higher entropy and creative variance. Best for brainstorming, creative writing, and open synthesis.

Top-P / Nucleus (P = 0.9)

Truncates long-tail low-probability tokens by dynamically sampling top cumulative 90% probability mass.

Presence Penalty (-2.0 – 2.0)

Penalizes tokens based on presence in generated text; positive values force model to introduce new topics.

Frequency Penalty (-2.0 – 2.0)

Penalizes tokens based on exact occurrence count; positive values reduce verbatim word repetition.

RAG Pipeline Steps

Command / PatternDescription
1. Document Chunking

Split raw corpus using recursive character splitting (500–1000 tokens) with 10–20% chunk overlap.

2. Dense Embedding

Convert chunks into dense vectors using embedding models (e.g. text-embedding-3-small).

3. Vector Indexing (HNSW)

Index embeddings in vector store using Hierarchical Navigable Small World graphs for fast ANN lookups.

4. Similarity Search

Query vector DB via Cosine Distance or Inner Product to fetch Top-K (K=3–5) context chunks.

5. Prompt Synthesis

Inject retrieved context chunks into System/User prompt template before executing generation.

Prompt Engineering Patterns

Command / PatternDescription
Role & Persona Pattern

Begin prompt with explicit expert domain role (e.g. 'You are a Principal Kubernetes Architect...').

Few-Shot Examples Pattern

Provide 2–3 input/output demonstration pairs prior to presenting the target problem query.

Chain-of-Thought (CoT)

Append 'Think step-by-step before producing your final answer' to force reasoning before generation.

Structured JSON Output

Specify explicit JSON schema structure in system prompt and set `response_format: { type: 'json_object' }`.

Transformer & Attention Formulas

Command / PatternDescription
Scaled Dot-Product Attention

Softmax((Q * K^T) / sqrt(d_k)) * V — computes pairwise contextual token weights.

Multi-Head Attention

Concat(head_1, ..., head_h) * W_O — projects queries/keys/values into parallel sub-spaces.

LoRA Weight Update

W = W_0 + (B * A) * (alpha / r) — trains low-rank adapter matrices while keeping base weights frozen.