Advances in Bioinformatics and Computational Biology by Unknown

Advances in Bioinformatics and Computational Biology by Unknown

Author:Unknown
Language: eng
Format: epub
ISBN: 9783030464172
Publisher: Springer International Publishing


Fig. 3.Examples of block-interchanges impacting Weighted Cycle Graph structures. In (a) we show an outcome of applying a BI in four black edges. In (b) we show a BI applied in three black edges, and in (c) a BI is a applied in two black edges.

Proof

Christie [6] tells we can increase the number of cycles by at most 2. Two scenarios are possible: either (i) one cycle is split in three, or (ii) two cycles are split in four by a single block-interchange .

Let us consider the first scenario, and let C be the cycle split in three. If C is balanced, the best we expect is that creates three balanced cycles, so . Otherwise, at least one of the resulting cycles shall be unbalanced, since weights of black edges of the three cycles sum up to a value different from the sum of gray edge weights. Therefore, the best we expect is to create at most 2 balanced cycles, so again .

Let us consider the second scenario, and let C and D be the cycles split by the BI. C generates and , while D generates and . If C is balanced, and could be both balanced, but if C is unbalanced, only one of them can be balanced. Therefore the change is by at most 1. The same applies for D and the cycles generated by the BI ( and ). Therefore, a BI can use both C and D to generate at most 2 new balanced cycles, so .



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