Roman law, history of private law, and comparative private law including e.g. inexistence, invalidity, and inefficacy (ineffectiveness) of legal transactions in Roman law and in its subsequent fate; responsibility in Roman private law (including custodia-liability); concept of contract in Roman law and in its subsequent fate; treasure trove in Roman law, in legal history, and in modern legal systems; law of succession in Roman law, in legal history, and in modern legal systems; pledge in Roman law, with special regard to the construction of ius offerendi.