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🚀 AI Systems EngineerID: aie-catastrophic-forgetting-rehearsal

Catastrophic Forgetting & Rehearsal

微调灾难性遗忘防范与重放
🎯Core Definition
Mitigating Catastrophic Forgetting via Experience Rehearsal & Parameter Freezing ensures that foundation models do not degrade in broad general intelligence, coding logic, or multi-lingual proficiency while fine-tuning on narrow domain datasets; core engineering strategies span: 1) Experience Rehearsal & Pre-training Data Mixing: co-mingling a 5%-20% ratio of high-entropy general instruction data (ShareGPT, GSM8k, code tokens) with domain samples to keep general neural representations active; 2) Parameter Isolation: utilizing PEFT/LoRA to freeze >99%>99\% of original backbone weights, rendering foundational knowledge physically immutable; 3) Spherical Linear Interpolation (SLERP / Weight Merging): blending fine-tuned checkpoints with base models via θmerged=(1λ)θbase+λθsft\theta_{\text{merged}} = (1-\lambda) \theta_{\text{base}} + \lambda \theta_{\text{sft}} to smoothen specialized parameters.
💡Use Cases
Domain-specific continuous fine-tuning, multi-task instruction scaling, and guarding against model degradation.
Key Problems Solved
Naive fine-tuning on domain data triggers catastrophic regression across standard benchmarks (MMLU/GSM8k collapsing by 50%+); rehearsal and parameter isolation maintain robust generalization.
🎯5 High-Frequency Exam Points
1
Explain why Full Fine-Tuning is significantly more susceptible to catastrophic forgetting compared to LoRA parameter isolation?
2
Analyze the Pareto trade-off of general-to-domain data mixing ratios (e.g. 10% general vs 90% domain) in preserving benchmark scores?
3
Why does Spherical Linear Interpolation (SLERP) outperform naive linear averaging when merging fine-tuned checkpoints?
4
How does KL-penalty loss regularization mathematically restrict policy drift away from the base model distribution during SFT?
5
Design an automated regression evaluation gate running MMLU, GSM8k, and HumanEval benchmarks before deploying fine-tuned weights?
🔗Foundational Prerequisite Cards (Click to Review)
Updated 2026-08-14
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