Thursday 16 August 2012

Assessing the impact of a design decision


Design agents evaluate the consequences of their decisions by inferring ahead
as to whether the decision value will satisfy constraints or support goals. In doing
so, it is likely that some of the information required in the inference process is not
yet available, and therefore the agent will attempt to substitute for it with an
expectation.

Figure 1. Design expectation example

Imagine the frame design agent, in our chair design problem, making a decision
about the frame material. Before committing to the design decision the agent
may verify whether the decision will satisfy cost constraints. Therefore it will
need to know the conditions that influence the cost, and the specific correlations
between the values for the determined conditions and the cost ranges. An expectation
such as the one described in Figure 1 could be critical in validating the
agent’s decision before all the cost components are known. Alternatively, the
frame design agent may take a decision which is perfectly valid at that point, that
will be used by other agents, only to be later invalidated in a cost analysis process.

Thursday 2 August 2012

Data Hoarding

Data hoarding releases currency, therefore changes object semantics. A receiver
hoards replicas from a sender and each replica is denoted as (objectID, semantics),
where semantics is either primary or copy.

General hoarding (G-hoarding): sender owns the primary of an object, i.e.
(objectID, primary), and receiver hoards a copy from the sender. After G-hoarding,
sender still owns the primary, i.e. sender (objectID, primary), and receiver
(objectID, copy).

Primary hoarding (P-hoarding): sender owns the primary of the object, i.e. (objectID,
primary), and receiver hoards the primary from the sender. After P-hoarding, the
primary is transferred from the sender to the receiver and the one in the sender
becomes a copy, i.e. sender (objectID, copy), and receiver (objectID, primary).

Copy hoarding (C-hoarding): sender owns only the copy of the object, i.e. (objectID,
copy), and receiver hoards a copy from the sender. After C-hoarding, both the sender
and the receiver hold copies, i.e. sender (objectID, copy), and receiver (objectID, copy).