| (_,Terms.Equation (l,_,_,Terms.Gt),_,_) as c ->
DT.index t l (Terms.Left2Right, c)
| (_,Terms.Equation (_,r,_,Terms.Lt),_,_) as c ->
DT.index t r (Terms.Right2Left, c)
| (_,Terms.Equation (l,_,_,Terms.Gt),_,_) as c ->
DT.index t l (Terms.Left2Right, c)
| (_,Terms.Equation (_,r,_,Terms.Lt),_,_) as c ->
DT.index t r (Terms.Right2Left, c)