@Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb = sb.append(this.indiceDeRegla).append(". (");

        for (int i = 0; i < this.causantes.size(); i++) {
            String s = this.causantes.get(i);
            sb = sb.append(s);

            if ((this.causantes.size() - 1) != i) {
                sb = sb.append('^');
            }
        }
        sb = sb.append(") --> ").append(this.producto);
        
        return sb.toString();
    }