We propose a novel approach for posterior sampling with intractable likelihoods. This is an increasingly important problem in scientific applications where models are implemented as sophisticated computer simulations. As a result, tractable densities are not available, which forces practitioners to rely on approximations during inference. We address the intractability of densities by training a parameterized classifier whose output is used to approximate likelihood ratios between arbitrary model parameters. In turn, we are able to draw posterior samples by plugging this approximator into common Markov chain Monte Carlo samplers such as Metropolis-Hastings and Hamiltonian Monte Carlo. We demonstrate the proposed technique by fitting the generating parameters of implicit models, ranging from a linear probabilistic model to settings in high energy physics with high-dimensional observations. Finally, we discuss several diagnostics to assess the quality of the posterior.

该研究提出了一种解决在科学领域中使用高级计算机模拟时出现的后验推断问题的新方法，这种方法使用学习的灵活的摊销估计量来近似似然-证据比率，并可以嵌入MCMC采样器中以从难以处理的后验中获得样本。

无似然马尔可夫蒙特卡洛与分摊的近似比率估计器