case classForbiddenArcLabel(token1: Int, token2: Int, arcLabel: Symbol) extends TransitionConstraint with Product with Serializable
A ForbiddenArcLabel constraint designates a transition as illegal if it would directly
create an arc (in either direction) with the specified label between the tokens at the given
indices. It also implicitly creates a RequestedArc constraint for the specified arc
(basically it says that we DO want an arc between the specified indices, just not with this
label).
Note that argument order (of the token indices) does not matter for the constructor.
A ForbiddenArcLabel constraint designates a transition as illegal if it would directly create an arc (in either direction) with the specified label between the tokens at the given indices. It also implicitly creates a RequestedArc constraint for the specified arc (basically it says that we DO want an arc between the specified indices, just not with this label).
Note that argument order (of the token indices) does not matter for the constructor.
index of the first token
index of the second token
label that is forbidden between the two tokens