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The purpose of this paper is to study a theory of systems and their models on the basis of studying the information channels between their elements, meaning that it is a continuation of those studies already carried out on the theory of systems and their models applied to environmental systems.

The model information transmission system (MITS) can be defined as the theoretical structure that makes it possible to describe the way information is stored and transmitted in a modelling process, and which will be completed in future studies. The basis for a taxonomy of languages is also presented.

The theoretical structure described will lead to the study of a theory of information from the point of view of the analysis of text systems and models, but analysed within the theoretical structure presented, which includes the study of an information source and an information channel.

These theoretical findings will improve the information channels used up to now for the study and modelling of systems and which are largely described using several computer programmes, as the information generated and transmitted will be studied and analysed in different ways. In this way, the text models and families of text models generated can be analysed by studying and transforming models, particularly by focusing attention on everything inherent to the information contained in the same.

The purpose of this paper is to carry out a theoretical study of the stability of the mathematical models defined in a class of systems. Furthermore, it will be supposed that the models have been obtained from experimental data and by means of the application of a methodology. The studies carried out in this paper are, on one hand, the theoretical framework for an analysis of the sensitivity and stability of a type of systems; on the other hand, they supplement the studies carried out by the authors, in which, using a computational program, the sensitivity of the mathematical models is analyzed with respect to a type of perturbation.

Initially, a class of systems is considered that are denominated quantifiable systems, in which model systems are defined that are determined by a set and a family of relationships. An initial study of the sensitivity of the mathematical models to perturbations in the experimental data lead to a concept of sensitive and stable models that forms the basis of the theory of stability developed in this paper. Furthermore, this permits a definition of the stability function for the set of the perturbations and, consequently, a determination of stable models according to the defined theoretical structure.

An analysis of the sensitivity and stability of mathematical models in quantifiable systems from a systems theory perspective will be fundamental for the determination of mathematical model stability in environmental systems.

The studies carried out in this paper supposes an advance in the study and modeling of a type of systems that the authors have denominated as quantifiable systems, applicable to the study of environmental systems and supplementing the numeric studies carried out by the authors.

A systematic study of a lotus's leaf area is described through the genetic improvement of Lotus glaber, an induced tetraploid population known as, Leonel, was obtained. Initial assessment showed an increase in dry material in comparison with a diploid population. The aim was to evaluate whether the increased production of forage found in the tetraploid population Leonel was due to increased foliolae sizes.

Three populations were studied L. glaber: diploid cytotype: seeds from a naturalised population of La Pampa Deprimida (Azul, Argentina); Tetraploid cytotype C1 seeds from the Leonel population, and Lotus corniculatus (Italia) seeds from Italy. Analysis of variance was carried out with a random design using a single factor, for the variables of area, length and width of the central foliolae. Linear and non‐linear model families were determined to estimate the area of the central foliolae. The selection criteria applied were: the best R², good efficiency, the greatest simplicity of the model and its stability.

The widths of the L. glaber diploid foliolae were less than those of L. corniculatus tetraploide and these were longer. The areas of the L. glaber foliolae were greater than those of the tetraploid L. corniculatus, and the areas of the foliolae of the diploid cytotype were slightly superior to the induced tetraploid cytotype L. Leoner. The best model was that which estimated the area of the central foliolae according to their width.

Non‐destructive estimates of foliar area were obtained for different species of the Lotus genus. The methodology chose provides a useful example of a systemic approach.

The variables studied are significant morphophysiological characteristics that can be used in programmes for the genetic improvement of L. glaber and L. corniculatus.

The authors continue developing a Linguistic Theory of the Ecological Systems, but in terms of the Semantics. Each symbol (transformed function) is syntactically a lexeme, carrying an associate sememe or atomic semantic unit. Each sememe can be decomposed in semes or quantic semantic unities. They are studied and semantic systems, associated with the syntactic, that serve them as suprastructure, in terms of two levels: the quantic and the atomic. Also, it is demonstrated that for all models of the complex reality, there will always exist a most complex model from the syntactic and semantic point of view.

Any mathematical model underlying a system of the complex reality (for example, in ecology, socioeconomy, etc.) defines a text written in a given language which belongs to a literature. A text‐model based language, L(M_T) is developed, which focuses on its syntax. Three generative grammars are built for its alphabet (lexic unities). Further, the linguistic entropy of this language is analyzed from the Vakar’s point of view. Finally, this theory is applied to a particular ecological model, as an example of a text written in L(M_T).

It is known that a mathematical ecological model and, in general, a particular methodology of modelling, can be considered a literary text written in a formal mathematical language. In this context, stylometric mathematical laws such as Zipf’s (range‐frequency and number‐frequency) can be applied to obtain information parameters in different semantic levels within the same model. Adapts several of these laws and introduces new elements, lexic units, operating and separating units, to carry out several statistical analyses upon two models or texts. The estimated slopes in the regression equations obtained in the present work are compared with the results of previous papers where Mandelbrot’s law was applied and comparisons between them are shown.

All models have in common that they encode experience and always involve signs, signals, syntax, semantics and an ability to decode and derive meaning from what is encoded. Therefore, an ecological model can be considered a text T, written in a formal (mathematical) language defined by the authors as L(M_T).

The language chosen is a regular language generated by regular grammars which in turn are generated by finite automaton.

A text results from a union of some finite automata defining a textual grammar. Recognoscitive and generative grammars of words, defining the basis of the L(M_T) language are developed.

A mathematical modelling of ecological systems is developed in parts I and II of this research project.

A language for ecological systems modelling has been defined and its implementation discussed.

The purpose of this paper is to present a further extension of the regular grammars of the language L(M_T).

This language may represent an ecological model, written in a formal mathematical structure.

The paper presents and develops recognoscitive and generative grammars of sentences (flow equations) together with a synonymy relationship, which characterize the L(M_T) language.

Provides a discussion of modelling of language.

Mathematical models are constructed at the interface between practice, experience and theories. The function of models puts us on guard against the privilege granted to what is accepted as abstract and formal, and at the same time puts us on guard against a static and phenomenological conception of knowledge. The epistemology of models does not suppress in any way the objectives of science: only, a dogmatic conception concerning truth is removed, and dynamic and dialectical aspects of monitoring are stressed to establish the most viable model. The purpose of this paper is to examine hybrid methodologies (inductive-deductive) that may either propose hypothetical causal relations and seek support for them in field data or detect causal relations in field data and propose hypotheses for the relations detected.

The authors follow a dialectical analysis for a type of inductive-deductive model.

In this work, the authors present an inductive-deductive methodology whose practical result satisfies the Hegelian dialectic. The consequent implication of their mutual reciprocal integration produces abstractions from the concrete that enable thought. The real problem in this case is a given ontological system or reality.

The essential elements of the models – variables, equations, simulation and feedback – are studied using a dialectic Hegelian theory.