From f10eb08a4cfe2718ccf66d3ff5788001211138e9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Nathan=20Lichtl=C3=A9?= <nathan.lichtle@gmail.com>
Date: Fri, 2 Aug 2024 15:20:21 +0200
Subject: [PATCH] Fix bug in target Q-value for illegal actions

Fix DQN bug: set ILLEGAL_ACTION_LOGITS_PENALTY to a large negative number instead of 0.
---
 open_spiel/python/pytorch/dqn.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/open_spiel/python/pytorch/dqn.py b/open_spiel/python/pytorch/dqn.py
index 7b5bc775e9..f027b115e6 100644
--- a/open_spiel/python/pytorch/dqn.py
+++ b/open_spiel/python/pytorch/dqn.py
@@ -30,7 +30,7 @@
     "Transition",
     "info_state action reward next_info_state is_final_step legal_actions_mask")
 
-ILLEGAL_ACTION_LOGITS_PENALTY = sys.float_info.min
+ILLEGAL_ACTION_LOGITS_PENALTY = torch.finfo(torch.float).min
 
 
 class SonnetLinear(nn.Module):