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																						$\Gamma$-CONVEXITY
											                            			 
						
                            			 
                            				Zhouqin Jia, Wenzhi Liu Liping Yuan, Tudor Zamfirescu
                            			 
                              			Acta mathematica scientia,Series B. 2025, 45 (1): 
																					3-15. 
																														DOI: 10.1007/s10473-025-0101-2
																				
                              			 
                              			
                                		
			                            	Let $\mathcal{F}$ be a family of sets in $\mathbb{R}^d\ (\mathrm{always}\ d\geq 2)$. A set $M\subset\mathbb{R}^d$ is called $\mathcal{F}$-convex, if for any pair of distinct points $x, y \in M$, there is a set $F\in \mathcal{F}$ such that $x, y \in F$ and $F \subset M$. We obtain the $\Gamma$-convexity, when $\mathcal{F}$ consists of  $\Gamma$-paths. A $\Gamma$-path is the union of both shorter sides of an isosceles right triangle. In this paper we first characterize some $\Gamma$-convex sets, bounded or unbounded, including triangles, regular polygons, subsets of balls, right cylinders and cones, unbounded planar closed convex sets, etc.  Then, we investigate the $\Gamma$-starshaped sets, and provide some conditions for  a fan, a spherical sector and a right cylinder to be $\Gamma$-starshaped. Finally, we study the $\Gamma$-triple-convexity, which is a discrete generalization of $\Gamma$-convexity, and provide  characterizations for all the  4-point sets, some 5-point sets and $\mathbb{Z}^{d}$ to be $\Gamma$-triple-convex.
			                             
                              			
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