Basic Dependency Modeling
– A phenomenon that follows and is caused by some previous phenomenon. One of
the elements in a dependency model.
– An entity—physical or conceptual—that is capable of producing a certain
effect. One of the elements in a dependency model.
– The relationship between a given element (event or agent) and another element
upon which it is causally dependent. The term is also used to refer to an
individual element in its role as a cause of a given element (e.g., "agent x is
a dependency of event z").
Dependency – A dependency that represents a direct causal
relationship (e.g. if agent x produces event z, we say that "x is a first-order
dependency of z").
Dependency – A dependency that represents an indirect causal
relationship (e.g. if agent w generates event x which triggers agent y to
produce event z, we say that "w is an nth-order dependency of z").
Statement – A representation of the first-order and/or nth-order
dependencies of a given event. Individual dependency statements almost never
exist in isolation, but rather appear as constituent statements within a
Dependency Statement – A dependency statement that represents all
dependencies that are directly or indirectly responsible for a given event.
Model – A representation of the causal relationships between
events and the other elements (events and agents) that enable those
events. Dependency models are comprised of multiple dependency statements that
collectively represent the causal interrelationships within a system, device or
Modeling – The process of generating a dependency model by
separately defining its constituent dependency statements. In many
applications, the individual events and agents within a dependency model
may be represented at such a low level that the model is most easily
manipulated using higher-level constructs and abstractions (such as those used
in Passive-Active Flow Modeling and Test Overlay Modeling).
(LogMod) – The name used by Ralph A. Depaul, Jr. to refer to
the causal modeling technique that he invented in the 1950s and which
would later become known as dependency modeling.
Event – An event within a dependency model that is represented by
a dependency statement that contains no dependencies. The initial events within
a dependency model correspond to the inputs of the system, device or process
that is represented by that model.
Event – An event within a dependency model that is not listed as a
dependency within another dependency statement. The terminal events within a
dependency model correspond to the outputs of the system, device or process
that is represented by that model.
– A term used to describe the topological relationship between a given element
(event or agent) in a dependency model and another element that is an nth-order
dependency of the given element (e.g., "an initial event is upstream from
those events and agents that it affects").
– A term used to describe the topological relationship between a
given element (event or agent) in a dependency model and another element
that contains the given element among its nth-order dependencies (e.g., "a
terminal event is downstream from those events and agents that have an
affect upon it.")
Dependency Model – A dependency model that contains a single set
of dependency statements and which is used for modeling a system, device or
process in which conditional causality does not come into play. Not to be
confused with single-signal modeling.
Dependency Model – A dependency model that contains multiple,
alternative sets of dependency statements (or a single set of dependency
statements that are modified dynamically) in order to support conditional
causality. In a diagnostic application, a multi-dimensional dependency model
can be used to represent test assymetry and changes to dependencies that result
from system state dynamics. Not to be confused with multi-signal modeling.