The subject of the presented work is the analysis of situations changeability in frame of constructed logic LCG. In the suggested interpretation, substantial change ('substantial movement'), which consists of the 'disappearing of a certain substance a1' and the 'coming into being' of substance a2, for which a1 is an 'active potentia', is understood in the following manner - the elementary fact: 'essence a1 exists' becomes fiction and a new fact arises: 'essence a2 exists', which is 'enabled' by the previous one. In the language of our formalisation this from fact to fiction, which occurs in the case of the situation: 'essence a1 exists', described as 'C-change'. The second component of substantial movement (or rather its situational equivalent) is the occurring of a new fact: 'essence a2 exists', which is 'possible' under the condition of an earlier occurring of the fact: 'essence a1 exists'. We describe this aspect of movement as 'G-change', which is an expansion of a set of formulas by a new elementary sentence and expressions in which this sentence occurs. Within the range of the LCG calculus operators C and G obtain an interpretation wider than the one which can be determined upon the basis of the Aristotelian theory of change expressed in terms of situational ontology. Semantical and syntactical characteristics of the LCG logic gives the possibility to compare it with such known calculi of changes like sentential systems of von Wright, Clifford and Wajszczyk.
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