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{
"lesson": "03-direct-preference-optimization-family",
"title": "The Direct Preference Optimization Family",
"questions": [
{
"stage": "pre",
"question": "Why can DPO skip training an explicit reward model?",
"options": [
"DPO trains its own reward model implicitly in a second optimization loop",
"The closed-form RLHF optimum lets you express reward as a log-ratio of policies, which substitutes into the Bradley-Terry loss",
"Preference data does not require a scalar reward",
"Bradley-Terry preferences happen to be invariant to the reward function"
],
"correct": 1,
"explanation": ""
},
{
"stage": "check",
"question": "What failure mode does IPO (Azar et al., 2024) primarily address in DPO?",
"options": [
"Requirement of paired data",
"Reliance on a reference policy",
"Length bias of the chosen response",
"Unbounded implicit reward gap from tiny preference probabilities"
],
"correct": 3,
"explanation": ""
},
{
"stage": "check",
"question": "When would you reach for KTO over DPO?",
"options": [
"When you must guarantee zero implicit-reward drift",
"When you have unpaired single labels (desirable / undesirable) and want to use loss-aversion utilities",
"When you have only paired data with strong margins",
"When you want to remove the KL penalty entirely"
],
"correct": 1,
"explanation": ""
},
{
"stage": "check",
"question": "Which property is unique to SimPO compared to DPO?",
"options": [
"It removes the reference policy and normalizes log-likelihood by sequence length",
"It drops the Bradley-Terry log-sigmoid for an identity mapping",
"It uses an odds-ratio loss with NLL",
"It keeps the reference policy and adds a margin"
],
"correct": 0,
"explanation": ""
},
{
"stage": "post",
"question": "What is the 'Degraded Chosen Response' problem in DPO that BPO targets?",
"options": [
"The chosen response is missing from the reference policy's support",
"The chosen response is sampled with low probability at inference",
"DPO can drive the chosen response's absolute log-prob down as long as the rejected log-prob falls faster",
"The chosen response becomes longer than the rejected"
],
"correct": 2,
"explanation": ""
},
{
"stage": "post",
"question": "Rafailov et al. (NeurIPS 2024) on scaling laws for direct alignment algorithms show:",
"options": [
"DAAs exhibit the same Gao et al. peak-and-collapse over-optimization shape on gold reward",
"DAAs eliminate Goodhart by design",
"Over-optimization disappears when paired data exceeds 100k examples",
"DPO over-optimizes but IPO and SimPO do not"
],
"correct": 0,
"explanation": ""
}
]
}