In mathematics, particularly graph theory, and computer science, a directed acyclic graph (DAG or dag / ˈ d æ ɡ / ()) is a directed graph with no directed cycles.That is, it consists of vertices and edges (also called arcs), with each edge directed from one vertex to another, such that following those directions will never form a closed loop. Facebook's initial public offering came on May 17, 2012, at a share price of US$38. The company was valued at $104 billion, the largest valuation to that date. The IPO raised $16 billion, the third-largest in U.S. history, after Visa Inc. in 2008 and AT&T Wireless in 2000. الرسم البياني لشبكة الأسلاك هو عبارة عن مخطط للأسلاك مبسط لدائرة كهربائية ويعرض مكونات الدائرة كأشكال مبسطة ووصلات الطاقة والإشارة بين الأجهزة.