post ảnh
18-08-2008, 10:28 AM
mình xin mượn tý đất nhé!
Bài 19/Chương 3:
http://www.forkosh.dreamhost.com/mimetex.cgi?G_1 = (http://www.forkosh.dreamhost.com/mimetex.cgi?X_1, http://www.forkosh.dreamhost.com/mimetex.cgi?E_1), http://www.forkosh.dreamhost.com/mimetex.cgi?G_2 = (http://www.forkosh.dreamhost.com/mimetex.cgi?X_2, http://www.forkosh.dreamhost.com/mimetex.cgi?E_2), http://www.forkosh.dreamhost.com/mimetex.cgi?G_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cle T, http://www.forkosh.dreamhost.com/mimetex.cgi?G_2 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cle T, với T = (X,E) , http://www.forkosh.dreamhost.com/mimetex.cgi?E_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?E_2 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cne http://www.forkosh.dreamhost.com/mimetex.cgi?%5Coslash . http://www.forkosh.dreamhost.com/mimetex.cgi?G_3 = http://www.forkosh.dreamhost.com/mimetex.cgi?G_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?G_2. CMR: http://www.forkosh.dreamhost.com/mimetex.cgi?G_3 liên thông.
Chứng minh:
Do http://www.forkosh.dreamhost.com/mimetex.cgi?E_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?E_2 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cne http://www.forkosh.dreamhost.com/mimetex.cgi?%5Coslash nên http://www.forkosh.dreamhost.com/mimetex.cgi?X_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?X_2 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cne http://www.forkosh.dreamhost.com/mimetex.cgi?%5Coslash.
Mà http://www.forkosh.dreamhost.com/mimetex.cgi?G_3 = http://www.forkosh.dreamhost.com/mimetex.cgi?G_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?G_2 = (http://www.forkosh.dreamhost.com/mimetex.cgi?X_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?X_2, http://www.forkosh.dreamhost.com/mimetex.cgi?E_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?E_2) là đồ thị.
Giả sử http://www.forkosh.dreamhost.com/mimetex.cgi?G_3 không liên thông.
http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cexists i, j http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cin http://www.forkosh.dreamhost.com/mimetex.cgi?X_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?X_2, i http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cnot%5Csim j trong http://www.forkosh.dreamhost.com/mimetex.cgi?G_3.
http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cbullet i, j http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cin http://www.forkosh.dreamhost.com/mimetex.cgi?X_1, mà http://www.forkosh.dreamhost.com/mimetex.cgi?G_1 liên thông http://www.forkosh.dreamhost.com/mimetex.cgi?%5CRightarrow giữa i, j có đường nối http://www.forkosh.dreamhost.com/mimetex.cgi?l_1 trong http://www.forkosh.dreamhost.com/mimetex.cgi?G_1.
http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cbullet i, j http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cin http://www.forkosh.dreamhost.com/mimetex.cgi?X_2, mà http://www.forkosh.dreamhost.com/mimetex.cgi?G_2 liên thông http://www.forkosh.dreamhost.com/mimetex.cgi?%5CRightarrow giữa i, j có đường nối http://www.forkosh.dreamhost.com/mimetex.cgi?l_2 trong http://www.forkosh.dreamhost.com/mimetex.cgi?G_2
Xét:
Trường hợp 1: http://www.forkosh.dreamhost.com/mimetex.cgi?l_1 = http://www.forkosh.dreamhost.com/mimetex.cgi?l_2 http://www.forkosh.dreamhost.com/mimetex.cgi?%5CRightarrow i, j được nối với nhau trong http://www.forkosh.dreamhost.com/mimetex.cgi?G_3 (trái với giả sử phản chứng) (1)
Trường hợp 2: http://www.forkosh.dreamhost.com/mimetex.cgi?l_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cne http://www.forkosh.dreamhost.com/mimetex.cgi?l_2 http://www.forkosh.dreamhost.com/mimetex.cgi?%5CRightarrow Trong T, i, j được nối với nhau bằng 2 đường đi khác nhau trong T.
http://www.forkosh.dreamhost.com/mimetex.cgi?%5CRightarrow T có ít nhất 1 chu trình. (trái giả thiết T là cây). (2)
Từ (1) (2) http://www.forkosh.dreamhost.com/mimetex.cgi?%5CRightarrow http://www.forkosh.dreamhost.com/mimetex.cgi?G_3 liên thông. http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cbox
link (http://www.toantin.org/forums/index.php?s=&showtopic=2796&view=findpost&p=21013)
Bài 19/Chương 3:
http://www.forkosh.dreamhost.com/mimetex.cgi?G_1 = (http://www.forkosh.dreamhost.com/mimetex.cgi?X_1, http://www.forkosh.dreamhost.com/mimetex.cgi?E_1), http://www.forkosh.dreamhost.com/mimetex.cgi?G_2 = (http://www.forkosh.dreamhost.com/mimetex.cgi?X_2, http://www.forkosh.dreamhost.com/mimetex.cgi?E_2), http://www.forkosh.dreamhost.com/mimetex.cgi?G_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cle T, http://www.forkosh.dreamhost.com/mimetex.cgi?G_2 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cle T, với T = (X,E) , http://www.forkosh.dreamhost.com/mimetex.cgi?E_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?E_2 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cne http://www.forkosh.dreamhost.com/mimetex.cgi?%5Coslash . http://www.forkosh.dreamhost.com/mimetex.cgi?G_3 = http://www.forkosh.dreamhost.com/mimetex.cgi?G_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?G_2. CMR: http://www.forkosh.dreamhost.com/mimetex.cgi?G_3 liên thông.
Chứng minh:
Do http://www.forkosh.dreamhost.com/mimetex.cgi?E_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?E_2 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cne http://www.forkosh.dreamhost.com/mimetex.cgi?%5Coslash nên http://www.forkosh.dreamhost.com/mimetex.cgi?X_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?X_2 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cne http://www.forkosh.dreamhost.com/mimetex.cgi?%5Coslash.
Mà http://www.forkosh.dreamhost.com/mimetex.cgi?G_3 = http://www.forkosh.dreamhost.com/mimetex.cgi?G_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?G_2 = (http://www.forkosh.dreamhost.com/mimetex.cgi?X_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?X_2, http://www.forkosh.dreamhost.com/mimetex.cgi?E_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?E_2) là đồ thị.
Giả sử http://www.forkosh.dreamhost.com/mimetex.cgi?G_3 không liên thông.
http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cexists i, j http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cin http://www.forkosh.dreamhost.com/mimetex.cgi?X_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Ccap http://www.forkosh.dreamhost.com/mimetex.cgi?X_2, i http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cnot%5Csim j trong http://www.forkosh.dreamhost.com/mimetex.cgi?G_3.
http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cbullet i, j http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cin http://www.forkosh.dreamhost.com/mimetex.cgi?X_1, mà http://www.forkosh.dreamhost.com/mimetex.cgi?G_1 liên thông http://www.forkosh.dreamhost.com/mimetex.cgi?%5CRightarrow giữa i, j có đường nối http://www.forkosh.dreamhost.com/mimetex.cgi?l_1 trong http://www.forkosh.dreamhost.com/mimetex.cgi?G_1.
http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cbullet i, j http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cin http://www.forkosh.dreamhost.com/mimetex.cgi?X_2, mà http://www.forkosh.dreamhost.com/mimetex.cgi?G_2 liên thông http://www.forkosh.dreamhost.com/mimetex.cgi?%5CRightarrow giữa i, j có đường nối http://www.forkosh.dreamhost.com/mimetex.cgi?l_2 trong http://www.forkosh.dreamhost.com/mimetex.cgi?G_2
Xét:
Trường hợp 1: http://www.forkosh.dreamhost.com/mimetex.cgi?l_1 = http://www.forkosh.dreamhost.com/mimetex.cgi?l_2 http://www.forkosh.dreamhost.com/mimetex.cgi?%5CRightarrow i, j được nối với nhau trong http://www.forkosh.dreamhost.com/mimetex.cgi?G_3 (trái với giả sử phản chứng) (1)
Trường hợp 2: http://www.forkosh.dreamhost.com/mimetex.cgi?l_1 http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cne http://www.forkosh.dreamhost.com/mimetex.cgi?l_2 http://www.forkosh.dreamhost.com/mimetex.cgi?%5CRightarrow Trong T, i, j được nối với nhau bằng 2 đường đi khác nhau trong T.
http://www.forkosh.dreamhost.com/mimetex.cgi?%5CRightarrow T có ít nhất 1 chu trình. (trái giả thiết T là cây). (2)
Từ (1) (2) http://www.forkosh.dreamhost.com/mimetex.cgi?%5CRightarrow http://www.forkosh.dreamhost.com/mimetex.cgi?G_3 liên thông. http://www.forkosh.dreamhost.com/mimetex.cgi?%5Cbox
link (http://www.toantin.org/forums/index.php?s=&showtopic=2796&view=findpost&p=21013)