From 22e4a733e0bf6dfa2b27947b679da27472753747 Mon Sep 17 00:00:00 2001 From: Varun Agrawal Date: Sun, 4 Dec 2022 18:36:36 +0530 Subject: [PATCH] Add details about the role of the HybridEliminationTree in hybrid elimination --- gtsam/hybrid/HybridEliminationTree.h | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/gtsam/hybrid/HybridEliminationTree.h b/gtsam/hybrid/HybridEliminationTree.h index 9b6854026..4802c2f89 100644 --- a/gtsam/hybrid/HybridEliminationTree.h +++ b/gtsam/hybrid/HybridEliminationTree.h @@ -24,7 +24,22 @@ namespace gtsam { /** - * Elimination Tree type for Hybrid + * Elimination Tree type for Hybrid Factor Graphs. + * + * The elimination tree helps in elimination by specifying the parents to which + * the "combined factor" after elimination should be assigned to. + * + * In the case of hybrid elimination, we use the elimination tree to store the + * intermediate results. + * Concretely, we wish to estimate the unnormalized probability P'(X | M, Z) for + * each mode assignment M. + * P'(X | M, Z) can be computed by estimating X* which maximizes the continuous + * factor graph given the discrete modes, and then computing the unnormalized + * probability as P(X=X* | M, Z). + * + * This is done by eliminating the (continuous) factor graph present at each + * leaf of the discrete tree formed for the discrete sequence and using the + * inferred X* to compute the `probPrime`. * * @ingroup hybrid */