**Efficiency**

Measure of how sparing of resources a simulation is when executing a complexity sets the lower bound on the required level of resources for correct simulation.

**Element**

Generic term to refer to, component or interaction

**Execution**

(By simulator of) Generation of model behavior by simulator obeying model instructions, rules or constraints,

**Experiment Design**

Systematic plan for executing a set of simulation runs with varied initial state and parameter assignments in order to efficiently explore model behavior within an experimental frame

**Experimental Frame**

(Informal) the conditions under which a system or a model are observed or experimented with.

The data space into which the behavior of an accommodating model or system will be placed.

**History**

A trajectory of system behavior or model behavior

**Homomorphic Model**

Model that stands in a holomorphic relation to another previous identified model. An isomorphic model is strong case of homomorphic model.

**Homomorphism**

(Informal): models such that the models exhibit the same behavior when started in corresponding states. The homomorphism concepts make it possible to test when for valid simplification. A state correspondence can be shown to be a homomorphism if corresponding states can be shown to

1.) Always transition to corresponding states under the same input, and

2.) To always yield the same (or equivalent) output.

**Input**

Variable : whose values are determined outside. A model. Think of the model as being fed this input through an external interface or input port and responding to them

**Input port**

Input variable. Terminology used to emphasize interface nature of input

**Interaction**

Static or dynamic constraint between elements of a model

**Interactive Simulation**

Simulation in which humans interact strongly with the model while it is being executed through its experimental frame. In virtual simulations the model is intended to be perceived as real. In components

**Isomorphic Model**

Homomorphic model for which the underlying state correspondence is a one-to-one mapping.

**Level of Abstraction**

(Informal): the degree to which a model has been abstracted from the system it is intended to represent. The higher the level, the greater the greater the abstraction (formal): level of abstraction is a relational concept. It refers to the relative position of the scope frames of models in the derivability partial ordering

**Level of Resolution**

The level of resolution of a model and its level of detail are strongly correlated; a high level of resolution implies a great amount of detail

**Live Simulation**

Interactive simulation in which real world elements may play the role of some of the model components. Example: a battle simulation may include real tanks firing blank rounds

**Lumped Model**

Target model in an aggregation or other simplification procedure

**Metric**

Mathematical measure for computing distance between two entities (points, curves, sets). Choice of metric and tolerance can be critical in judging validity of a model

**Model**

(Informal): rules, equations, and/or constraints for generating behavior resembling that of a system (formal): specification of behavior in a dynamic modeling formalism other meaning:

Physical, mathematical, or logical representation of a system, entity, phenomenon, or process

**Modeling Formalism
**mathematical language for expressing models

**Nondeterministic Model**

Model in which the input and state do not uniquely determine the next state and. In a probabilistic model (or stochastic model), the possible next states and outputs are constrained by probability distributions.

**Output**

Variable whose values are determined by a model. Think of the model generating these outputs through an external interface output ports

**Output Port**

Output variable. Terminology used to emphasize interface nature of input