Primitive component

The term collectivism has sometimes been used to distinguish this AL philosophy from the more traditional top down and bottom up philosophies. Collectivism embodies the belief that in order to properly understand complex systems, such systems must be viewed as coherent wholes whose open-ended evolution is continuously fueled by nonlinear feedback between their macroscopic states and microscopic constituents. It is neither completely reductionist (which seeks only to decompose a system into its primitive components), nor completely synthesist (which seeks to synthesize the system out of its constituent parts but neglects the feedback between emerging levels). 

The term modeling refers to a process of determining an appropriate description of reality that approximates its behavior to some specified degree of accuracy. Models are constructed using well-understood primitive components, or building blocks, defined by their inherent functionality and also their interaction mechanism. 

To develop a distributed modeling system, it is necessary to identify the primitive components essential to the fundamental operation of the system and its various appended and programmable functions, a process referred to as kernel identification. Studying such systems provides much of the basis for acquiring insight into what structure and function a kernel should possess (9). 

A module instantiation statement can be written within a module declaration. A synthesis system treats such a module instance as a black box and does not take further action, that is, the module instance appears in the synthesized netlist as if it were a primitive component. Here is an example of a full-adder module that contains one module instantiation statement. Notice that in the synthesized netlist, shown in Figure 2-67, the module MyXor appears just as it is described in the top level module FullAdderMix. 

An outstanding question is how much of the mantle still maintains high volatile concentrations. This involves resolution of the nature of the high He/" He OIB-source region. Most models equate this with undepleted, undegassed mantle, although some models invoke depletion mechanisms. However, none of these has matched the end-member components seen in OIB lithophile isotope correlations. It remains to be demonstrated that a primitive component is present and so can dominate the helium and neon isotope signatures in OIB. The heavy-noble-gas characteristics in OIB must still be documented. It is not known to what extent major volatiles are stored in the deep Earth and associated with these noble gas components. 

For example, terrestrial Xe has typically been modeled as starting with a primordial U-Xe composition (very similar to solar wind Xe), and then experiencing (a) isotopic fractionation, (b) addition of radiogenic Xe, and (c) addition of heavy Xe isotopes derived from fission of (Pepin 2000). Martian Xe doesn t quite work that way. Swindle et al. (1986) first pointed out that U-Xe (Pepin 2000) will not work as the primordial Martian Xe. Instead, they found that except for an enrichment of radiogenic Xe, Martian atmospheric Xe could be modeled as isotopically fractionated AVCC Xe (at the time considered a primitive component, now considered a mixture of Q-Xe and Xe from presolar diamonds (Ott 2002, this volume)). In that model there would be no need for any " " Pu fission Xe. In fact, there would be no room for any. This would be strange because " " Pu has a longer half-life than the I would decay away first, yet... 

There are two stable isotopes of helium, He and " He, which vary in their ratio by over three orders of magnitude in terrestrial samples. The Earth s atmosphere is well mixed with respect to helium and contains helium with a uniform isotopic composition of He/" He = 1.39 x 10 . Atmospheric helium is a convenient standard for helium isotope determinations, and terrestrial He/" He ratios are usually normalized to the air ratio and expressed in units of R/Ra, where R = He/ He and Ra = ( He/ He) . In contrast to atmospheric helium R/Ra = 1), the radiogenic helium produced by a-decay of U and Th series isotopes has a much lower ratioof R/Ra0.1, while the volcanic helium that is derived from the Earth s mantle is highly enriched in He R/Ra =5-30). Thus volcanic helium has an isotopic composition distinct from other sources such as atmospheric helium or the helium produced by radioactive decay. This He-rich mantle helium is sometimes called primordial helium, since it is thought to be the remnant of a primitive component... 

From what has been said above, one can conclude with respect to the sixteen immediate materials of plants that they can be reduced in their last analysis to three or four principles that are their primitive components, namely, hydrogen, carbon, oxygen, and sometimes nitrogen and that these materials differ from each other only with respect to the diverse proportions of their constituting elements. ... 

To gain the knowledge about the architecture of the whole OS in terms of software component composition and bindings, we can use Architecture Description Language [12] as the specification of the architecture of the system. This language has the possibility to capture interface types (with method signatures), primitive components (in terms of provided and required interfaces), composite components (an architectural compositions of primitive components) and the bindings between the respective interfaces of the components. 

Vertical compliance. Also called substituability. The goal is to check whether it is possible to replace a set of primitive components that are nested inside a composite component by the composite component itself. In other words, this compliance can answer the question whether the architecture description of the system is sound with respect to the hierarchical composition of the components. 

The key features of software systems with respect to behavior and architecture checkers are the granularity of the individual primitive components, the level of isolation and complexity of the communication mechanism between them. Large... 

Horizontal and vertical compliance checking can be done exhaustively. This is a fundamental property which allows the reasoning about the dependability of the entire component-based OS. Assuming that the lower-level verification methods (described in Sections 3.1 to 3.7) prove some specific properties of the primitive components, we can be sure that the composition of the primitive components into composite components and ultimately into the whole OS does not break these properties. 

The feasibility of many lower-level verification methods from Sections 3.1 to 3.7 depends largely on the size and complexity of the code under verification. If the entire OS is decomposed into primitive components with a fine granularity, it is more likely that the individual primitive components can be verified against a large number of properties. Thanks to the recursive component composition we can then be sure that these properties also hold for the entire system. 

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