arXiv subjects
Publications and source records attributed to Julia Ninova.
In the paper different kinds of proof of a given statement are discussed. Detailed descriptions of direct and indirect methods of proof are given. Logical models illustrate the essence of specific types of indirect proofs. Direct proofs of Lehmus-Steiner's Theorem are proposed.
The paper presents a method for obtaining problems whose conclusions contain disjunctive propositions. These problems constitute a version of inverse problems with a given logical structure. The logical models in the groups of problems studied have been interpreted comprehensively. Equivalent problems have been given by keeping or not keeping the condition of homogeneity in their conclusion.
By suitable examples we illustrate an algorithm for composition of inverse problems.
The conditions determining that two triangles are congruent play a basic role in planimetry. By comparing not congruent triangles with respect to given sets of corresponding elements it is important to discover if they have any common geometric properties characterizing them. The present paper is devoted to an answer of this question. We give a generalization of criteria A and D for congruence of triangles and apply it to prove some selected geometric problems.