Sets of Intervals on the Straight Line

On Collinear Sets in Straight-Line Drawings

Given a planar graph G on n vertices, let fix (G) denote the maximum k such that any straight line drawing of G with possible edge crossings can be made crossing-free by moving at most n − k vertices to new positions. Let v̄(G) denote the maximum possible number of collinear vertices in a crossingfree straight line drawing of G. In view of the relation fix (G) ≤ v̄(G), we are interested in exampl...

Straight Line Embeddings of Planar Graphs on Point Sets

Universal Sets for Straight-Line Embeddings of Bicolored Graphs

A set S of n points is 2-color universal for a graph G on n vertices if for every proper 2-coloring of G and for every 2-coloring of S with Research was supported by the project 1M0545 of the Ministry of Education of the Czech Republic and by the grant SVV-2010-261313 (Discrete Methods and Algorithms). Viola Mészáros was also partially supported by OTKA grant K76099 and by European project IST-...

Upward Straight-Line Embeddings of Directed Graphs into Point Sets

In this paper we consider the problem of characterizing the directed graphs that admit an upward straight-line embedding into every point set in convex or in general position. In particular, we show that no biconnected directed graph admits an upward straight-line embedding into every point set in convex position, and we provide a characterization of the Hamiltonian directed graphs that admit u...

survey on the rule of the due & hindering relying on the sheikh ansaris ideas

قاعده مقتضی و مانع در متون فقهی کم و بیش مستند احکام قرار گرفته و مورد مناقشه فقهاء و اصولیین می باشد و مشهور معتقند مقتضی و مانع، قاعده نیست بلکه یکی از مسائل ذیل استصحاب است لذا نگارنده بر آن شد تا پیرامون این قاعده پژوهش جامعی انجام دهد. به عقیده ما مقتضی دارای حیثیت مستقلی است و هر گاه می گوییم مقتضی احراز شد یعنی با ماهیت مستقل خودش محرز گشته و قطعا اقتضاء خود را خواهد داشت مانند نکاح که ...