An example of a framework based on norm-aware agents is described by L ´opez y L ´opez in [L ´opez y L ´opez,2003;L ´opez y L ´opez et al.,2001;L ´opez y L ´opez and Luck, 2002]. This framework defines normative agents as those agents whose behaviour is shaped by the obligations they must comply with and prohibitions that limit the kind of goals that they can pursue. To this extent the author defines a norm frame which includes addressees (the agents to whom the norm applies), beneficiaries (those who the addressees are focused on), normative goal (the goal that is to be achieved or avoided as specified by the norm), contexts (the states of the environment when the norm is active), exceptions (states when the norm is not active) and rewards and punishments (responses to the compliance or violation of a norm). This norm frame (describing what is supposed to be achieved/avoided in which context) is then linked to actions by means of a relation between a specific action and a norm. Either an action benefits a norm (making it possible to be compliant with the norm when the action is executed) or it hinders a norm (executing the norm makes it impossible to be norm-compliant). It is then stated that, for a normative agent, all actions benefiting the norms are permitted and all actions that hinder the norms are prohibited. In
[L ´opez y L ´opez and Luck, 2002] the authors define different stages through which a norm goes since it is established until it becomes abolished. This, seen as the norm’s lifecycle, includes stages such as issue, spread, adoption, modification, abolition, activation, compliance, reward, violation, sanction, dismissal and non-sanction.
A framework for formally specifying electronic institutions, described as a dialogic framework by the creators, is AMELI, based on the ISLANDER formalism [Esteva and Sierra,2002;Esteva et al., 2002]. This abstraction considers an agent-based institution as a dialogic system within which, the interactions are composed by different dialogic activities. The latter, also named illocutions [Noriega, 1997], are made up by agent group meetings, called scenes, that comply to well-defined protocols. Breaking up the interactions into scenes permits the framework to be characterised by modularity, similarly to other popular programming techniques such as Object Oriented Program- ming. Special normative rules capture actions’ consequences through illocution schemes (illocution formulas containing possibly unbound variables and thus representing a set of possible illocutions) and determine when norms (obligations) are activated and get fulfilled. A feature of ISLANDER/AMELI is that they use regimentation in order to make sure that the norms are always followed. In other words, no deviation from or ignoring of norms by the agents is allowed. Another limitation is that the agent is not aware of the norms and there is an external mediator that filters unwanted behaviour. AMELI was the first fully implemented institutional framework providing tools able to parse ISLANDER specifications and execute them at runtime.
The HARMONIA methodology of [V´azquez-Salceda,2004;V´azquez-Salceda and Dignum, 2003] proposes a different approach, by explicitly specifying the norms of the institu- tion and keeping track of the refinement steps taken to track all the translations needed to implement the abstract norms of the institution. The framework distinguishes four different levels: an abstract level (which contains the abstract norms), a concrete level (containing concrete instantiations of the abstract norms), a rule level (where concrete norms are translated into rules that can be computed by the agents), and a procedure level (where the final mechanisms to follow the rules are implemented). The use of such a layered approach shows its benefits in situations when changes to the norms are required (which happens often in real-world institutions). Since connections be- tween the implemented mechanisms and the abstract norms that they relate to are made explicit, a change to the (abstract) norms can be propagated through the sys- tem. HARMONIA also tries to solve (part of) the restrictive regimented nature of the ISLANDER formalism, by the proposal of Police Agents, agents which are responsible for the enforcement of the norms. This allows to control the system’s safety (avoid non-desirable situations due to some agent’s failure), while still providing the agents (enough) autonomy to perform their tasks in manners that were not thought of at design, therefore enabling them to handle unforeseen situations and adding a level of robustness to the system. There exists no implementation supporting this framework, but parts of HARMONIA have been included in OMNI (see Section2.2.2.3.3).
In [Aldewereld, 2007], Aldewereld further extends the ideas of V´azquez-Salceda in [V´azquez-Salceda,2004] by applying parts of the methodology to highly-regulated en- vironments (environments governed by many of complex norms). The author makes a distinction between “substantive” (expressing wanted and unwanted situations and al- lowing the possibility of violations) and “regimented” (expressed as direct constraints on the agent’s actions and therefore always ensuring compliance) norms and deals mainly with the first type. [Aldewereld,2007] identifies four important aspects of in- stitutional implementations: 1) an ontology to allow communications between agents, and to express the meaning of the concepts used in the norms; 2) an (explicit) norma- tive description of the domain, specifying the allowed interactions in the institution, presented in a format readable by (norm-aware) agents; 3) a set of protocols (con- ventions) that agents that are incapable of normative reasoning can use to perform their assigned task; and 4) an active norm enforcement to see to it that the norms specified for the domain are adhered to and order and safety is guaranteed in the system. These four elements are combined into a framework that gives the relations between laws and electronic institutions. Moreover, (formal) methods are specified for the implementation of norm enforcement and the (automatic) creation of protocols (based on constraints specified by the norms). However, there is no implementation of this framework, although some concepts are included in OMNI and ALIVE (see Section2.2.2.3.3).
In [Kollingbaum et al., 2008] the authors present a framework called Requirement- driven Contracting (RdC), for the automatic formation of executable norms from requirements and correlated relevant information. Requirements include domain as- sumptions, preferences, and priorities. With the help of templates and formal language constructs, the designer writes the environment specification (ES) to translate require- ments into system objectives, domain assumptions into domain restrictions, and spec- ifies preferences over objectives and priorities over clashing preferences. The last ones are put into the RdC algorithm to acquire an executable specification of norms that regulates, as a consequence, the virtual organisation.
2.2.2.3.3 Hybrid Organisational-Institutional Models for Normative Multi-Agent