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LEVEL 3 · ADVANCED · INDIVIDUAL TRACK

Level 3 Systems Glossary

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Level 3 Systems Glossary

Use these terms precisely. They describe different layers of a production AI system: how a model computes, how it is served, how it is aligned, how it is evaluated, and how operators observe it. A technical founder should be able to ask which metric moved, which layer owns the risk, and what evidence supports a change.

Term Working definition
MoE Mixture of Experts; routes tokens to a subset of specialist parameter blocks.
Sparse attention Attention that considers selected token relationships rather than every pair.
FlashAttention Memory-efficient exact attention algorithm that reduces I/O overhead.
PagedAttention KV-cache layout that pages memory to improve serving utilization.
vLLM Open-source inference engine known for PagedAttention and continuous batching.
TGI Text Generation Inference, a model-serving stack from Hugging Face.
TensorRT-LLM NVIDIA optimization and serving toolkit for LLM inference.
Triton GPU programming language/compiler often used for custom inference kernels.
KV cache management Allocation, reuse, eviction, and sharing of attention key/value state.
Prefix caching Reusing computation for identical prompt prefixes, such as system policy.
Speculative decoding A small draft model proposes tokens a larger model verifies.
Batched inference Processing multiple requests together to use hardware efficiently.
Continuous batching Adding and removing requests from a live inference batch.
Chunked prefill Splitting long prompt processing so decode traffic remains responsive.
Tensor parallelism Splitting model tensors across devices for one model invocation.
Pipeline parallelism Splitting model layers into stages across devices.
ZeRO Optimizer-state and gradient sharding approach from DeepSpeed.
DeepSpeed Microsoft training/inference system with distributed optimization tools.
FSDP Fully Sharded Data Parallel; shards model state across workers.
RLHF Reinforcement learning from human feedback.
RLAIF Reinforcement learning from AI feedback.
DPO Direct Preference Optimization; learns preferences without a separate reward loop.
IPO Identity Preference Optimization; a preference-learning variant.
KTO Kahneman-Tversky Optimization; uses desirable/undesirable labels.
GRPO Group Relative Policy Optimization; compares sampled responses within groups.
ORPO Odds Ratio Preference Optimization; combines likelihood and preference learning.
Constitutional AI Alignment approach using written principles to guide critique and revision.
Self-play Training through competition or interaction with copies of a policy.
Tool-use RL Reinforcement learning that rewards correct external-tool behavior.
Agent RL Reinforcement learning over multi-step agent trajectories.
PPO Proximal Policy Optimization, a clipped policy-gradient method.
TRPO Trust Region Policy Optimization, constraining policy update size.
Reward model Model that predicts preference or quality for a response.
Reward hacking Optimizing the score while missing the intended outcome.
Sycophancy Agreeing with a user’s premise rather than correcting it.
Mode collapse Reduced diversity in generated outputs or learned behavior.
Capability elicitation Prompting or scaffolding to reveal a model’s latent ability.
Red team Authorized adversarial testers seeking harmful or bypass behavior.
Blue team Defenders operating controls, detection, and response.
Purple team Collaborative red/blue work that validates defenses.
Model card Documentation of a model’s intended use, limits, data, and risks.
System card Documentation of a deployed system, including integrations and controls.
Eval card Documentation of an evaluation’s scope, dataset, metrics, and limits.
MMLU Broad multiple-choice benchmark across academic subjects.
HellaSwag Benchmark for commonsense sentence completion.
HumanEval Python coding benchmark scored by tests.
MBPP Mostly Basic Python Problems coding benchmark.
GSM8K Grade-school math word-problem benchmark.
MATH Competition-style mathematics benchmark.
BIG-Bench Community benchmark suite spanning many tasks.
HELM Holistic Evaluation of Language Models framework.
TruthfulQA Benchmark probing false-but-plausible answers.
Arena Elo Relative ranking from pairwise user preferences.
LMSYS Organization associated with Chatbot Arena and model evaluation.
Offline eval Evaluation on a fixed dataset before release.
Online eval Evaluation using live or live-like traffic after release.
A/B test Randomized comparison of variants across user cohorts.
Interleaved test Presents blended ranking results to compare systems efficiently.
Canary metrics Health metrics for a limited-release cohort.
Guardrail metrics Rates and outcomes of safety-policy decisions.
Drift metrics Measures showing input, output, or outcome distribution change.
Telemetry Operational signals emitted by a system.
Span Timed, attributed unit of work inside a trace.
Trace Linked record of work for one request or transaction.
Event Discrete business or system occurrence.
Log Timestamped diagnostic record.
Structured logging Logs encoded as queryable fields rather than free text.
PII redaction Detecting and removing or masking personal information.
Tokenization Converting text into model-readable token IDs.
BPE Byte Pair Encoding tokenization based on merged frequent pairs.
SentencePiece Tokenizer framework that treats text as a raw byte sequence.
Unigram Tokenization model selecting likely subword pieces from a vocabulary.
Vocabulary Set of token units a tokenizer can emit.
Context window Maximum tokens a model can consider in one invocation.
Sliding window attention Limits attention to nearby tokens to support long sequences.
RoPE Rotary Positional Embeddings encoding relative token position.
ALiBi Attention with Linear Biases, a positional-bias technique.
Positional encoding Signal that gives a transformer token-order information.

The point is not memorization. Use the vocabulary to connect a lease-renewal assistant’s user-visible latency to queueing, KV cache behavior, model routing, safety decisions, and business outcomes. That is systems design.

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