In this paper we classify competitive markets using a new form of normalized Herfindahl index and the degree of dominance of the leader. For this purpose we use the notion of copula, which connects two or more random variables with given marginals. The parameters of the two marginals (which are...

Amid the controversies around the optimisation criteria and the objective functions when applying mathematical methods in economics, we proposed a method of quantifying a multi-criteria optimum, called critical distance method. The demonstration of this method is exemplified by assessing the...

In this paper we proposed a model deriving from physics laws, which are associated to the investments impact upon the economic system potential. Defining several physics fundamental dimensions and starting from a series of assumptions, we tried to find their possible economic meaning and...

A balanced economic development is essentially based on self-financing of investment cycle. The efficient use of energy resources and raw materials could rise by increasing the renewal of fixed capital, which is meaning also a shift to a higher technological level. From this correlation is...

Empirical data show during the historical process of economic development profound structural changes in economy. One of the most important movements is from stages where the so-called tangible investments are predominant to those where intangible investments become predominant. Applying some...

To estimate long-run growth based on the so-called potential GDP became a constant preoccupation among economists. However, one remaining problem in every long-run growth model is to estimate a persistent trend in labour productivity outside of it, in order to avoid the implicit circular...

The paper aims to model the underground economy using two different models: one based on the labor supply method and a generalized model for the allocation of time. The model based on the labor supply method is conceived as a simulating one in order to determine some reasonable thresholds of the...

There is a long period since the problem of public debt sustainability captures the attention of economists. However, there is no unanimity concerning an adequate unique sustainability indicator or function generally accepted. Just in this line of elaborating new models and improving...

The study concentrated on demonstrating how non-linear modelling can be useful to investigate the behavioural of dynamic economic systems. Using some adequate non-linear models could be a good way to find more refined solutions to actually unsolved problems or ambiguities in economics. Beginning...

Using some special models, this study tries to quantify the size of underground economy in Romania. The exposition plan includes: 1) Models based on direct approaches; 2) Models based on indirect approaches; 3) A generalised model for the allocation of time; 4) A model based on May’s logistic;...