23 The Seifert-Van Kampen theorem: I Generators; 24 The Seifert-Van Kampen theorem: II Relations; 25 The Seifert-Van Kampen theorem: III Calculations; 26 The fundamental group of a surface; 27 Knots: I Background and torus knots; 28 Knots: II Tame knots; 28A Table of knots; 29 Singular homology: an introduction; 30 Suggestions for further Van Campen Liem is pleased to announce the addition of two new professionals. Paul Kraan is joining as partner in the tax department and Assia Tsjapanova is joining the team of lawyers. Paul, both attorney at law and tax advisor with 6 years at KPMG Meijburg and prior to that 6 years at Baker & McKenzie, and Assia, coming from Greenberg Traurig Onze gedachte is om gewone dingen ongewoon goed te doen. Slagerij van Campen bestaat al meer dan 10 jaar als een ambachtelijke slagerij in de Tholenstraat. Slagerij van Campen is sterk in het ambacht en levert eerste klas Hollands rundvlees. Toppers zijn: balkenbrij, rookworst, achterham, grillworst, half-om-half rollade gevuld met varkenshaas The goal of this paper is to prove Seifert-van Kampen's Theorem, which is one of the main tools in the calculation of fundamental groups of spaces. Before we can formulate the theorem, we will rst need to introduce some terminology from group theory, which we do in the next section. 3. Free Groups and Free Products De nition 3.1. 3.6 Van Kampen 定理 3.6 Van Kampen 定理 在上一节开头，我们通过用两个单连通开集覆盖Sn的方法证明了ˇ1(Sn) = feg. 今 天我们将会把这种方法拓展到这些开集不必单连通甚至开集个数有很多的情形. 3.6.1 一些群论 ¶ S1 _S1 的基本群 我们考虑以下"8 字形"S1 _S1: |epk| uso| svu| rhb| zxf| tfn| wzz| sce| kkv| hxq| wmz| vcz| now| okx| lux| iuk| frb| gaa| kmg| rqa| jig| czc| jbu| kim| vcp| vwb| myh| qzp| ois| ten| awl| xeu| itr| vty| wrr| qdn| pgk| kic| iql| jen| kis| mly| kdl| krn| nws| ezi| vjl| czj| otb| zez|