让期权模型同时精准计算价格和隐含波动率,提升训练效率与稳定性。
PIVOT: Bridging Black-Scholes Implied-Volatility and Price Objectives via Differentiable Jäckel Operator

- 提出可微分的PIVOT层,保持原有求解器精度并避免分支逻辑反向传播
- 在H100上实现每秒17.9亿次隐含波动率计算,误差小于9.3e-14
- 在标普500等多资产上显著降低价格和波动率误差,效果优于基线
现代期权学习系统在价格空间与隐含波动率(IV)空间间存在接口瓶颈:尽管Jäckel的‘让我们理性’(LBR)求解器已能以机器精度高效反演布莱克-斯科尔斯价格,但缺乏一个可微分层来保留前向传播中的LBR行为,且避免在反向传播中陷入其分支逻辑。本文提出PIVOT——价格-隐含波动率目标转换器,保持LBR前向不变,通过平滑的布莱克-斯科尔斯/布莱克-76价格映射进行隐式微分,引入显式门控机制:无效域返回NaN,良好条件行获得精确1/vega梯度,低维数区域则衰减而非静默正则化。单个H100上,融合的Triton核达到1.79e9 IV/s,最大相对误差为9.3e-14(对比参考C求解器);端到端标签生成速率在合成链上达48.9M/s,SPX OptionMetrics上为16.6M/s。在超隐含波动率(HyperIV)风格的一日重现任务中,增强型目标的帕累托占优基线,持有外价格平均绝对误差(MAE)降低最高达43.4%;最强三种子门控目标使价格MAE下降38.8%,隐含波动率MAE下降21.3%。跨资产结果在RUT、VIX、NDX上分别实现40.1%、24.2%、16.7%的价格误差改进,而无门控的隐含波动率回环控制退化至近零表面,验证了门控作为正确性契约而非调参旋钮。
原文摘要 · Abstract (English)
Modern option-learning systems operate in two coordinates: price space, where markets quote and no-arbitrage constraints are most naturally enforced, and implied volatility (IV) space, where volatility surfaces are smoothed, regularized, and evaluated. The bottleneck is interface, not approximation: Jäckel's seminal "Let's Be Rational" (LBR) solver already inverts the Black-Scholes price to machine precision efficiently. What is missing is a differentiable layer that preserves LBR in the forward pass and avoids backpropagating through its branch logic. Such a layer must also confront the unavoidable singularity of the inverse map in the low-vega regime, where the sensitivity 1/vega diverges as vega -> 0. We close this gap with PIVOT, the Price-Implied-Volatility Objective Translator. PIVOT keeps the LBR forward pass intact and supplies the backward pass by implicit differentiation through the smooth Black-Scholes/Black-76 price map, with an explicit gating contract: invalid domains return NaN, well-conditioned rows receive the exact 1/vega gradient, and low-vega rows are attenuated rather than silently regularized. On a single H100, a fused Triton kernel reaches 1.79e9 IV/s at machine precision (9.3e-14 max relative error vs. the reference C solver); end-to-end label generation sustains 48.9M/s on synthetic chains and 16.6M/s on SPX OptionMetrics. In a HyperIV-style one-day reproduction on SPX, PIVOT-augmented objectives Pareto-dominate the baselines, reducing held-out price MAE by up to 43.4% and the strongest three-seed gated objective improving price MAE by 38.8% and IV MAE by 21.3% jointly; cross-asset results on RUT, VIX, and NDX show directional price-MAE gains of 40.1%, 24.2%, and 16.7%, while an ungated IV-roundtrip control collapses to a degenerate near-zero surface, confirming the gate as a correctness contract rather than a tuning knob.
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