Moreover, the more customary topics are leavened with some 'pleasant surprises', such as the author's attractive theory of decomposition of graphs into 3-connected '3-blocks', an interesting and remarkable approach to electrical networks, and - perhaps particularly - the classification theorem for closed surfaces.
Saka, ang mas kaugalian paksa ay lebadurahan na may ilang 'kaaya-aya sorpresa', tulad ng sa may-akda ng kaakit-akit teorya ng agnas ng mga graphs sa 3-connected '3-blocks', isang kagiliw-giliw at kapuna-puna sa elektrikal at network, at - lalo na marahil - ang pag-uuri teorama sarado na para sa ibabaw.