0404132人目の素数さん
2018/05/16(水) 05:01:23.77ID:iriy4b81以下、第(2)集 No.60 からのコピペ >>394
xx・xx = x・x^3 = x・x つまり xx はベキ等。
〔補題〕 xxyy = yyxx, ……(6)
xx=X,yy=Y はベキ等だから、
X -Y = (X-Y)^3 = X^3 -Y^3 -XYX +YXY = X -Y -XYX +YXY,
XYX = YXY,
XY = (XY)^3 = (XYX)(YXY) = (YXY)(XYX) = (YX)^3 = YX,
(xy)^2 = xx(xy)^2 = (xy)^2・xx,
xy = (xy)^3 = (xy)^3・xx = (xy)xx … (7)
(xy)^2 = (xy)^2・yy = yy(xy)^2
xy = (xy)^3 = yy(xy)^3 = yy(xy) …… (8)
xとyを入れ替えて
yx = xx(yx) …… (9)
(8)*(7)
(xy)^2 = yy(xy)・(xy)xx = y(yx)^3・x = y(yx)x = yy・xx = xx・yy,
xとyを入れ替えて
(xy)^2 = (yx)^2,
xy = (xy)^3 = (xy)(yx)^2 = x(yyxy)x = x(xy)x = yx …… (10)