← 🧠 Foundations of LLMs & GenAINEXT IN FOUNDATIONS OF LLMS & GENAIConstitutional AI and RLAIF→
Core
Reward Models
A reward model converts human preference comparisons into a scalar score for any response, the very signal RLHF chases. Trained on response pairs labeled by which one a human favored, it learns to rank instead of to write text. Its flaws are behind RLHF's failure modes: reward hacking (gaming the proxy) and going stale once the policy drifts off-distribution. AI, ML, and GenAI interviews probe it because it shows where the alignment signal originates and why it is exploitable, and the same idea carries over to LLM-as-judge evaluation.
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RELATED CONCEPTS
PRACTICE THIS IN REAL QUESTIONS
LLM & GenAI FundamentalsWalk through RLHF, then explain DPO and why it has largely displaced PPO-based RLHF.→LLM & GenAI FundamentalsAfter RLHF, your model is safer but worse at hard tasks. How do you manage the alignment tax?→LLM & GenAI FundamentalsYour RLHF model games the reward model instead of being genuinely helpful. How do you stop reward hacking?→LLM & GenAI FundamentalsExplain PPO and GRPO for LLM alignment. Why did GRPO drop the value model?→LLM & GenAI FundamentalsWhat is Constitutional AI / RLAIF, and how does it differ from RLHF?→LLM & GenAI FundamentalsBeyond DPO: what are SimPO, KTO, and ORPO, and why do these alignment variants exist?→
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