From: Christian Bauer <Christian.Bauer@uni-mainz.de>
Date: Fri, 10 May 2002 19:02:41 +0000 (+0000)
Subject: reactivated an epsilon-tensor simplification hack because of a user request
X-Git-Tag: release_1-0-9~9
X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?a=commitdiff_plain;h=427388b46ece3de8af727032f0801e0d5805b78e;p=ginac.git

reactivated an epsilon-tensor simplification hack because of a user request
---

diff --git a/ginac/tensor.cpp b/ginac/tensor.cpp
index 587a8170..fb2e596e 100644
--- a/ginac/tensor.cpp
+++ b/ginac/tensor.cpp
@@ -510,10 +510,14 @@ bool tensepsilon::contract_with(exvector::iterator self, exvector::iterator othe
 
 	} else if (other->return_type() == return_types::commutative) {
 
-#if 0
-		// This handles eps.i.j.k * p.j * p.k = 0
-		// Maybe something like this should go to simplify_indexed() because
-		// such relations are true for any antisymmetric tensors...
+#if 1
+		// This handles eps.i.j.k * p.j * p.k = 0 and related cases.
+		// Actually, simplify_indexed() can handle most of them on its own
+		// but one specific case that is not covered there is
+		//   eps~mu.nu~i~j * p.mu * p~nu
+		// because of the difference in variance in the dummy indices mu
+		// and nu. Eventually, simplify_indexed() should be extended to
+		// handle this case, and this hack removed.
 		exvector c;
 
 		// Handle all indices of the epsilon tensor