We study data-driven multi-period lost-sales inventory control under censored demand, where a stockout reveals only that demand exceeded the stocking level. We develop a unified, model-based framework for policy learning from censored data, built on a new cost decomposition for base-stock policies and a biased sample-average approximation (SAA) approach. The cost decomposition allows us to propose a new coverage condition under which censored observations are informative enough for sample-efficient policy learning. Guided by this coverage condition, we design two biased SAA algorithms: an upper-biased one that achieves near-optimal sample complexity under the offline coverage condition, and a lower-biased one that actively generates the required coverage and achieves near-optimal regret online. More broadly, this biased SAA approach provides a general principle for implementing pessimism and optimism under censored feedback, which may be of independent interest.
Figures & tables
Setup
Work
Stationary demand
Censored observations
Leading-order Result
Offline sub-optimality gap with N trajectories
Qin et al. (2023)
✗
✗
O(MT3/2/N)
Xie et al. (2024)
✗
✗
O(MT/N)
This work
✗
✓
O(MT/N⋆)
This work
✓
✓
O(MT/Nagg⋆)
Online episodic regret over K episodes
This work
✗
✓
Θ(MTK)
This work
✓
✓
Θ(MKT)
Table 1: Comparison of sub-optimality and regret guarantees for learning multi-period inventory policies. N⋆ and Nagg⋆ denote the effective sample sizes and its time-aggregated version under censored observations, where N⋆≥N and Nagg⋆≥NT in the uncensored setting.
Notation
Interpretation
Notation
Interpretation
Ft∈RM
[Ft]j=Ft(j) for j∈[M−1]+
Wt⋆∈RM+1
Order-up-to value under the optimal policy
Dt⋆∈RM
Discrete derivative of Wt⋆
At(s)∈RM×M
[At(s)]ij=μt,i−j1{i≥j≥s}
ct∈RM
[ct]j=(ht+bt)Ft(j)−bt
qt∈RM
[qt]j=σt1{j∈[αt,βt)}P(xt≤j∣x1=0)
ut∈RM
[ut]j=σt1{j∈[αt,βt)}P(xt⋆≤j∣x1=0)
vt∈RM
[vt]j=P(yt⋆≤j∣x1=0)−P(yt≤j∣x1=0)
Table 2: Summary of notations in Section 3 , where the estimated versions W^t , D^t , A^t(s) , and c^t are defined analogously by replacing Ft with F^t and μt with μ^t .
F^t(k+1)(j):=max{F^t(k)(j),FtLCB,(k+1)(j)},
(6.4)
Algorithm 2 DP-LCB
Figure 1: Panel (a) plots the DP-UCB gap versus the number of trajectories N ; panel (b) plots the adequate-coverage curves versus the effective sample size N⋆ . Experiments are conducted under a seasonal truncated-Poisson instance with M=30,T=6 and st⋆∈{7,…,17} , with 150 repetitions. In each trajectory, the logging policy draws Bt∼Uniform{0,…,U} each period and orders up to ytb=max{xt,Bt} .
Figure 2: Performance gap under partial coverage. DP-UCB is compared with vanilla DP and SAIL on an instance with M=30 and T=12 over 200 repetitions; the demand distributions are detailed in Appendix C . Panel (a) plots the sub-optimality gap versus N with N∈{128,192,256,512,1024} . Panel (b) plots the distribution of learned first-period base-stock levels at N=192 across 200 repetitions.
Figure 3: Online regret under censored feedback. DP-LCB is compared with vanilla DP and SAIL-CE on an instance with M=30 and T=12 over 60 repetitions, with demand distributions detailed in Appendix C . Panel (a) plots cumulative regret versus the number of episodes K , up to K=2048 . Panel (b) shows how the mean value of the learned first-period base-stock levels changes across episodes, over 60 repetitions.