Databases Reference
In-Depth Information
Zadeh does not abandon the quest for justifiability, but instead re-
sorts to modifications of conventional logic that are compatible with
linguistic and fuzzy understanding of nature and consequences.
2 Complexes
When events happen, there are usually other related events. The entire col-
lection of events is called a
complex
. The events can be called the elements of
the complex.
A “mechanism” [30] or a “causal complex” [8] is a collection of events
whose occurrence or non-occurrence results in a consequent event happening.
Hobbs' causal complex is the
complete
set of events and conditions necessary
for the causal effect (consequent) to occur. Hobbs suggests human casual rea-
soning that makes use of a causal complex does not require precise, complete
knowledge of the complex.
Each complex, taken as a whole, can be considered to be a granule.
Larger complexes can be decomposed into smaller complexes; going from
large-grained to small-grained. For example, when describing starting an au-
tomobile, A large-grained to small-grained, nested causal view (Fig. 1) would
start with
When an automobile's ignition switch is turned on, this
causes
the
engine to start.
But, it would not happen if a large system of other nested conditions were
not in place.
There has to be available fuel. The battery has to be good. The switch
has to be connected to the battery so electricity can flow through it.
The wiring has to connect the switch to the starter and ignition system
(spark plugs, etc.). The engine has to be in good working order; and
so forth.
start car: turn on ignition switch
...
available
fuel
good
battery
wires
connect:
battery,
ignition
switch
wires
connect:
ignition
switch,
starter,
spark
plugs
turn on
ignition
switch
working
fuel
pump
intact
fuel
lines
fuel
in
tank
Fig. 1.
Nested causal complex
