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Transformer Architecture and Attention Questions

Comprehensive understanding of Transformer architecture and attention mechanisms including the principles of self attention where queries keys and values are used to compute attention weights with appropriate scaling. Understand scaled dot product attention and multi head attention and why parallel attention heads improve representational capacity. Know positional encoding schemes including absolute positional encodings relative positional encodings rotary position encodings and alternative methods for injecting order information. Be able to explain encoder and decoder components feed forward networks residual connections and layer normalization and their role in training stability and optimization. Discuss attention variants and efficiency improvements such as sparse attention local windowed attention linear attention kernel based approximations and other methods to reduce memory and compute cost along with their trade offs. At senior and staff levels be prepared to reason about scaling Transformers to very large parameter counts including distributed training strategies parameter and data parallelism memory management and attention pattern design for long sequences and efficient inference. Be ready to apply this knowledge to sequence modeling language modeling and sequence transduction tasks and to justify architectural and implementation trade offs.

HardTechnical
0 practiced
Discuss the trade-offs of pre-norm versus post-norm Transformers when scaling to very deep stacks. Explain effects on gradient flow, convergence behavior, initialization sensitivity, and how optimizers like Adam or LAMB interact with normalization placement. Propose experiments to validate claims at scale.
EasyTechnical
1 practiced
Compare encoder-only, decoder-only, and encoder-decoder Transformer topologies. For each topology, list typical tasks (e.g., classification, language modeling, seq2seq), describe structural differences and decoding patterns, and explain how you would decide which topology to adopt for a new product.
MediumTechnical
1 practiced
Design an experiment and strategy to prune attention heads to compress a Transformer model with minimal performance loss. Describe metrics, pruning criteria (magnitude, importance, learned gates), retraining schedule, and how you'd validate generalization across downstream tasks.
HardTechnical
0 practiced
Propose a combined compression strategy that uses attention-head merging, low-rank approximations of projection matrices, and structured pruning to reduce compute and memory for a large Transformer. Describe how to apply these techniques jointly, the expected speed/size gains, and an evaluation plan to measure performance degradation and recovery.
HardTechnical
0 practiced
A distributed training job using ZeRO Stage 2 runs out of memory during gradient accumulation. Outline a step-by-step debugging checklist and configuration changes to resolve the OOM without significantly hurting throughput, including checks for accidental tensor retention, offloading options, micro-batch adjustments, and ZeRO tuning knobs.

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