Name: Rolf Mertig (email_not_shown)
Date: 02/08/06-01:36:24 PM Z

Sure. This is all fine. But also straightforward.

>So, I was wondering if there is something inside FC...
Actually, Frederik added ExplicitLorentzIndex and some
rules for Eps.

>From the source code of Eps.m :

lor := lor = MakeContext["LorentzIndex"];
(*Added ExplicitLorentzIndex. 21/9-2002. F.Orellana*)
exlor := exlor = MakeContext["ExplicitLorentzIndex"];
mom := mom = MakeContext["Momentum"];

Eps[a__?(MatchQ[#,_Integer|exlor[_Integer]]&), ru___Rule] := Signature[{a}];

Eps[a___, n1_. (lor|exlor)[mu_,___], b___, n2_. (lor|exlor)[mu_,___],c___ ] := 0 /;
 NumberQ[n1 n2];
Eps[a___, n1_. mom[mu_,___], b___, n2_. mom[mu_,___],c___ ] := 0 /;
 NumberQ[n1 n2];

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