Definitions.II.doc 2/25/05
n. abstraction:
a description or representation abstracted
from another description or representation.
v. abstraction: the process of removing
concrete and particular detail from a description or representation.
The concrete and particular details removed are
left undescribed or unrepresented and subject to inference by the audience.
n. actor: an entity identifiable by an
observer as a cause of an effect; an entity that performs [a part]; an entity
that participates in a process or representation
as in a pre-specified script. The
general sense is that of an observer identifying an entity that acts or causes
things to happen. Technically, such an entity is an OO object with the ability
to schedule its own actions.
n. agent: an actor
playing a role or acting on behalf of something else.
Notes:
1)
The best definition of "agent" in the literature: "An autonomous
agent is a system situated within and a part of an environment that senses that
environment and acts on it, over time, in pursuit of its own agenda and so as
to effect what it senses in the future." [1]
[1]
Franklin, S. and Graesser, A. "Is it an Agent, or just a Program?: A
Taxonomy for Autonomous Agents" in Intelligent Agents III. Agent Theories, Architectures, and
Languages. ECAI'96 Workshop (ATAL), Budapest, Hungary, August 12-13, 1996,
Proceedings. Müller, Jörg P.;
Wooldridge, Michael J.; Jennings, Nicholas R. (Eds.) 1997.
2)
The IE root ag- "To drive, draw, move." Also the IE root of "axiom".
3)
The definition of agent-based might seem to present a contradiction because it
is ontological; but the definition of "actor" assumes the capability
(or actuality) of an actor being observable.
Ultimately, however, "identifiability" is an ontological
characteristic that doesn't imply that an observer actually exists. So, there is no contradiction.
adj. agent-based: something formulated
with or built up from agents; a statement
whose components are agents or whose salient
characteristics arise from agents. Agents in this sense
are akin to axioms and assertions.
adj.
agent-directed: a process or statement guided,
constrained, or controlled by an agent. Technically, this is ontological and is
agnostic about how a system is viewed or thought about.
adj.
agent-oriented: a statement which is easy to understand, interpret, or
develop in terms of agents. Technically, this is epistemological and describes the way a system is thought about or understood and is agnostic about
the system's ontological status.
n. algorithm: a finite set of well-defined actions for accomplishing some task
which, given an initial state, will result in a corresponding recognizable
end-state.
n. applicability: the state or degree
of being applicable.
adj.
applicable: capable of being
applied. This means that if A can be applied to B, then A has a
characteristic that gives evidence of a particular usage relationship to B.
v. apply: to put to use; to employ.
tv. apply: to have relevance or a valid connection.
n. assertion: a statement
that acts as an atomic or composite element of an argument or representation; an emphatic statement;
an affirmation; a claim that a given state or situation is the case. The Indo-European root is "ser-"
"to line up" or "to arrange". Assertions carry the connotation that they are well-formed or
syntactically correct statements. They also connote a skepticism as to their
veracity.
n. attribute: a characteristic or quality,
inherent in or ascribed to, someone or something. Syn: property. In
computing, an attribute is a named value or relationship that exists for some
or all instances of some class and is directly associated with that instance or
that class.
v.
attribute: to regard as a characteristic or quality of a
person or thing, including a cause effect relationship. Syn. ascribe, impute.
n. calibration: the confirmation of
and/or adjustment to parameters such that standard inputs result in standard
outputs.
adj.
complex: consisting of interconnected or
interwoven parts; composed of two or more units; involved or intricate. Technically, a complex system
has many cause-effect relationships or one in which it is difficult to tease
out cause-effect relations.
n. complexity: a measure of
the number of constituents of a system and their degree
of interconnection. Technically, the
resource requirements and representation
difficulty associated with a model or simulation is a
direct function of its complexity.
Note: Typically, the complexity
increases with the amount of detail, i.e., simulating a model that has many
components, and interactions, each described with high resolution is likely to
require great resource consumption no matter what simulator is used. Under this assumption, for fixed resource
availability, there must be a tradeoff between scope and resolution in a
simulated model.
adj.
concurrent: operating or acting in
conjunction with another; being in accordance; harmonious; contributing to the
same event or effect. Technically, a
partial ordering where any component can be directly preceded or succeeded by
more than one other component.
Notes: 1) The gist of the word is to cooperate, to meet, to coincide, to
run together.
2)
The order parameter for sequence and concurrency is usually time; but,
it doesn't have to be. It can be any
monotonically increasing magnitude.
When the order parameter is not time, sequence and concurrency refer to
the dependence of one constituent upon another. For example, components in a data-driven computation will be
capable of starting whenever their input is available regardless of any other
components that also require the same input data state.
n. concurrent simulation: a simulation in which actions are partially ordered such
that some actions are independent and might, in principle, happen at the same
time or be executable regardless of the execution of
other actions.
n. concurrent simulator: a simulator that facilitates concurrent simulations.
n.
constructive model: a type of constructive proof or argument where the model is built to demonstrate characteristics of the models
referent. It is axiomatic in that all
components of the model are built from a given set of
primitives and no outside interaction is allowed.
n. constructive proof: a method
of proof that demonstrates the existence of a mathematical object with certain
properties by creating or providing a method for creating such an object.
n. constructive simulation:
an implementation of a model which is composed of
primitive building blocks and the behavior of the simulation
arises solely from those building blocks and not from outside interference.
n. correct model: a model that is valid in every relevant characteristic.
n. correct simulation: a simulation that is verifiable in every relevant
characteristic.
n. correct simulator: a simulator that generates correct
simulations.
n. correctness: The degree to which some thing is free of error.
n. crossmodel validity:
synonym for validity.
Validity assumes two or more models. Sometimes, however, an assumption is made
stating that the truth is accessible and one model is more
real than another. Crossmodel validity
is used to emphasize that two models are being compared
rather than comparing one model to a real system.
n. derivability: the state or degree of
being derivable.
adj.
derivable: capable of being derived. This means
that if C can be derived from A, then C and A have characteristics that give
evidence of a particular inheritance relationship from A to C.
v. derive:
to generate a new thing from a source thing; to arrive at by
reasoning. Syn: infer.
n. detail: an individual part or item; a
particular; a characteristic considered individually and in relation to a
whole; a minor or an inconsequential item or aspect; a minutia; a discrete part
or portion of a thing. A detail is
concretely associated with a thing or situation. It is not abstract.
n. distributed simulator: a simulator that uses multiple components (possibly
geographically remote) to execute the actions of a simulation.
n.
execution: a particular carrying out of a procedure or set of actions. An instance of computational inference.
v.
extrapolate:
to infer or estimate by extending or projecting known information.
n. extrapolation: a result arrived at through
inference from an initial state.
n. formal system: a type of formalism, particularly as defined by:
1. A set of symbols or "undefined
terms."
2. A constructive (explicit mechanical)
procedure for assembling the symbols into formulae.
3. An initial set of formulae, assumed to
be true, called axioms.
4. A set of inference rules for deriving
new formulae from previous formulae.[*]
Technically,
formal systems take the form of logical or mathematical inference systems.
[*] Following Gödel, 1934. "On Undecidable Propositions of Formal
Mathematical Systems" in "The Undecidable" ed. Davis, Martin.
n. formalism: any doctrine emphasizing form and
de-emphasizing content where instances of the doctrine manipulate symbols
independent of their referents; an instance of such a doctrine.
adj. granular: consisting of or appearing
to consist of small particles; a composite (non-atomic) thing; a thing that has
distinguishable constituents; divisible; (math) an analytic thing.
n. granularity: the degree to which a
thing is granular.
n. homomorphic models: 2 or
more models such that homomorphisms
can be defined between them.
n. homomorphism: a morphism
exhibiting similarities between the two objects. Technically: Let X and Y be objects such that Cx is a characteristic
of X and Cy is a characteristic of Y. A
morphism f: X -> Y is a homomorphism if f(Cx) = Cy.
n. hysteresis: the degree to which a system is dependent on its previous states; the sum of all
metastable states of a system.
v. inherit: to obtain or receive a
characteristic or thing from a predecessor or ancestor.
n. inscription error: the error of
inscribing a set of characteristics into a representation
and then observing those characteristics or their direct consequences
from the system as an independent empirical discovery or
result. Technically, inscription error
is the conflation of experimentation (discovering characteristics of a device)
with verification (ensuring that a synthetic device
does what you designed it to do).
n. interaction: mutual influence or the
reciprocal actions between more than one entity.
n. interactive simulation: an implementation of a
model whose execution or outcome
depends on interaction with the external
environment.
n.
level of resolution: the granularity
of a resolution; the extent to which a representation shows constituents or details.
n. measure: dimension, quantity, or capacity as
ascertained by comparison with a standard.
A distinguishable characteristic of a system that
can be quantified. Syn: observable.
n. measurement: value exhibited by an
observable.
n. model: a physical, mathematical, or logical
representation of a referent system,
entity, phenomenon, or process such that a homomorphism
can be defined between the representation and
the referent. The similarities
exhibited by the homomorphism might include but are
not limited to behavior or structure.
n. modeling formalism: a formalism for expressing models. Specifically, a modeling formalism is a set
of symbols and rules that encourage the separation of the symbols from their
referent and manipulation of those symbols independent from the referent, but where
those symbols have definite unambiguous referents.
Note: All computer models and
simulations are formal systems. But,
there exist modeling formalisms that are not formal systems. In particular, graphical models,
(unimplemented) mathematical equations, etc. are not formal systems because
they lack the mechanical procedure for assembling formulae. A mathematical equation can be considered a
formula within the larger formal system of mathematics; but, by itself, it is
not a formal system. It needs a machine
or integrator to execute it. A
graphical model is a formula but the machine by which new formulae are created
resides in the thing or person doing the drawing.
n. morphism: an abstract directional
relationship between two different objects.
Technically: Let X and Y be objects of any kind. Then a morphism f is defined as a
relationship from X to Y, denoted by f: X -> Y such that the following
operations are defined for the morphism:
Domain: X = dom(f)
Codomain: Y = cod(f)
n. parallel: having comparable parts, analogous
aspects, or readily recognized similarities; having the same tendency or
direction; continuing a resemblance through many particulars; applicable in all essential parts; alike; similar.
Note: The gist of the word is to
be alike, to have the same properties or tendencies.
n. parallel simulation: a concurrent simulation in which some actions
are executed simultaneously.
n. parallel simulator: a distributed simulator where the components
carry out similar actions.
Note: The distinction between a
parallel simulator and a non-parallel distributed simulator lies in the
heterogeneity of the actions performed by the components. Parallelism is directly proportional to the
homogeneity of the actions.
n. petitio principii: the deductive
logical fallacy of inferring a conclusion that is already stated as an
assumption; "begging the question".
n. plectics:
the study of the separability of a system into
constituent parts and the relationships between systemic and constituent
phenomena.
Note: Plectics was coined by Dr. Murray Gell-Mann in
"Let's Call It Plectics", an article in Complexity Vol. 1, No. 5,
1996. In that article, he states that
the words "simple" and "complex" both descend from the
Indo-European root "plek-". Using
it directly neatly avoids the cardinality that "simple", denoting 1,
and "complex", denoting more than 1, specify. This makes it more appropriate as a moniker
for studying the complexity, or lack thereof, of systems.
v. predict: to declare or state in advance
on the basis of observation, experience, or scientific reason.
n. prediction: an assertion
specifying some future state. A
prediction may or may not be an extrapolation.
n. predictive validity: the
believability or strength of a prediction. Technically, a model
will be predictively valid if it has generated many valid predictions or if the prediction was arrived at by extrapolation
from a valid initial state using a valid
model.
n.
replicative validity: similarity
between the data characteristics of two or more representations,
statements, or assertions. Technically, this is the degree to which two
assertions have the same or equivalent effect. In particular, when two assertions
are replicatively valid, they can serve as substitutions
or replacements for one another. The
strictest form of this is a homomorphism between
data elements of two representations.
n.
representation: a statement
providing a likeness, description, or demonstration of some thing; an attempt
at a complete rhetorical position, description of a state of affairs, or a
point of view; an execution, 'acting out', or
performance of a meaningful sequence of events (as in a theatrical
performance).
n.
resolution: a statement
or explanation that resolves a thing or provides a
method for resolving some thing.
Technically, a resolution of a thing is a representation
of the constituents of that thing and how those constituents interact.
resolution (music): in western tonal music theory is the
"need" for a sounded note and/or chord to move from a dissonance or
unstable sound to a more final or stable sounding one, a consonance. Resolution has a strong basis in tonal
music, since atonal music generally contains a more constant level of dissonance
and lacks a tonal center to resolve to.
resolution(microscopy): the minimum distance
between distinguishable objects.
resolution(images): has something to do with
graininess or how much information is (can be) contained in an image.
v. resolve: to separate the component parts
of; to reduce to the constituent elements; to reduce to simple
or intelligible notions; to make clear or certain; to free from doubt; to
disentangle; to unravel; to explain; to cause to perceive or understand; to
acquaint; to inform; to convince; to assure; to make certain. Technically, resolving is an act of
"cutting up", analysis, and distinction.
adj.
sequential: Consisting of a sequence of
things in fixed succession; arranged in a determined order. Technically, a total ordering where each
component is preceded by only one other component and succeeded by only one
other component.
adj.
similar: related in appearance or nature;
having characteristics that correspond exactly or nearly. Technically, it means of the same class or
kind, where the class or kind is defined by membership functions or
predicates. This implies that there
must be some characteristics upon which the similarity is based. E.g. simultaneity - at the same time.
n. similarity
measure: extent to which two observables take on the same value or
magnitude.
adj.
simple: consisting of only one or very few
parts or components; having straightforward or obvious meaning, implication, or
consequence; having little or no ornamentation; being a fundamental or
rudimentary element; having no divisions or branches; not compound. Synonyms: naive, sincere, ordinary, common,
basic, atomic, unitary. Technically, a
simple system has very few cause-effect relationships and
is relatively easy to understand or interpret.
n. simulant:
A person who spends a lot of time creating, using, or studying simulation.
v. simulate (1a) to have or take on the
appearance, form, or sound of; imitate, mimic; (1b) to make in imitation of or
as a substitute for; (2) to make a pretense of; feign; (3) to realize, act out,
or effect a representation or model
of. Technically, to execute a set of
actions and show effects similar to another thing.
n. simulation: a real, implemented, or instantiated model; a situated or embedded model; a
set of actions such that, when executed, affect the environment.
Notes:
1)
A simulation is an effective model in the sense that it has a lasting effect on
its environment. I.e., it is not just a
metaphysical, logical, computational, or mental construct.
2)
A simulation is an effective equivalent intended to trick or to fool in a
satisficing but ultimately incomplete way.
It is limited to the context of the characteristics being
simulated. The degree to which the simulation
and the simulated characteristics agree is variable; but, there is always a
notion of a "good enough" match.
Simulation is distinct from emulation.
3)
The use of the term simulation carries implications about the similarity
relationship between the simulator and the simulation. There is an implication that the similarity
(including a homomorphism) is somewhat analytic, meaning that if the
referent is decomposable, the simulation is decomposable and the similarity
extends down into the components. But,
the implication is that the similarity is incomplete and it is possible (or
easy) to distinguish between the simulation and its referent. A simulation is ultimately a sham, a fake,
or specious in some way. Again, these
implications are dependent on subjective characteristics and require an
observer.
4)
There are also ontological implications to the term that imply a simulation is
removed enough from its referent to be considered autotelic and important in
and of itself, regardless of any correlation to a referent. In critical theory, this point of view is
put forth by Baudrillard as a copy of a copy which has been so dissipated in
its relation to the original that it can no longer be said to be a copy, stands
on its own as a copy without a model.
It is this sense of the term that generates the technical distinction
between a model and its implementation where a simulation is an implementation
of the model as executed by a simulator as in DEVS.
n. simulator: one that simulates,
especially an apparatus that generates characteristics approximating those of
the referent.
n. solution: a statement
or explanation that solves a problem or provides a method
for solving a problem.
n. solution set: a statement of the initial situation and the outcome
associated with a solution.
v. solve: to clear up or explain something
puzzling or unintelligible; to arrive at a desirable outcome given some initial
situation; (logic) to infer correctly.
n. statement: the formal expression of
facts or opinions in language (not nec. verbal or textual); a well- or
ill-formed expression, sentence (as in logic), testament or declaration
(explicit formal announcement); a position in an ongoing debate; a summary of a
state of affairs (as in a financial statement). This carries no implication that the expression is correct or
well-formed. Statements can be
recursive, meaning they can consist of other statements.
n. static
modeling formalism: a modeling formalism
where the doctrine and the symbols do not change over time or due to
iteration. Technically, the rules for
symbol manipulation are only capable of generating trajectories that exhibit no
state (or memory) dependence. Models in static modeling formalism
do not exhibit hysteresis.
n. structural validity: compositional
similarity between two or more representations, statements, or assertions. Technically, this is the degree to which two
assertions have the same or analogous components or
mechanisms. In particular, when two assertions are structurally valid,
there are clear mappings between the components of one and those of the
other. The strictest form of this is a homomorphism between components or mechanisms of two representations.
n. system: a group of interacting, interrelated, or
interdependent elements forming a whole; functionally related group of elements,
especially; a set of objects or phenomena grouped together for classification
or analysis.
Note: The use of the word
"system" assumes a separation between things internal and external to
the system. It implies that the object
can be treated either as a collection of components or as a unit. The behaviors of components internal to the
system are the generative mechanisms for the behavior of the system as a whole.
adj.
valid: a
believable, convincing, well-grounded, or strongly argued statement,
assertion, or representation.
n.
validity: the believability or strength of a statement, assertion, or representation.
Technically, validity is the degree to which an assertion
can be trusted as true enough or true to within some tolerance.
n. verification: (1) the act of verifying. (2a) a
confirmation of truth or authority. (2b) the evidence for such a
confirmation. (2c) a formal assertion of validity. Technically, the process of determining where
two statements agree and disagree as in comparing a model to its corresponding simulation.
v. verify: (1) to argue the truth of by presentation
of evidence or testimony; substantiate. (2) to determine or test the truth or
accuracy of, as by comparison, investigation, or reference; regulate by
conducting a parallel experiment or comparing with
another standard. Technically, to
compare and contrast two or more statements.
n. verity: the quality or condition of being true,
factual, or trustworthy.
Note: Verity is distinguishable
from validity. Verity targets
ontological truth, regardless of any arguments or belief. Validity targets effective formal systems
and conclusions that follow from premises.
The result is that, in M&S, verification becomes the
incontrovertible differences between a model and its implementation whereas
validation becomes the arguable relationship between a representation and
reality. One cannot verify a
representation against reality because of the ontological wall. One can only validate a representation
against reality. However, one can verify
one representation against another. One
can also validate one representation against another. Validation can be considered a weak type of verification or
verification can be considered a strong type of validation. So, although they are distinguishable, they
both target the same issue: trust.