小妹在看Bartle的實變
對於兩段課文不是很清楚 以下兩個黃色部分 麻煩大家了..謝謝..：
1. An ordered pair (χ,Χ) consisting of a set χ and a σ-algebra Χ of
subsets of χ is called a measurable space.
Let χ be the set Ｒ of real numbers. The Borel algebra is the
σ-algebra Ｂ generated by all open intervals (a,b) in Ｒ.
Observe that the Borel algebra Ｂ is also the σ-algebra generated by
all closed intervals [a,b] in Ｒ. Any set in Ｂ is called a Borel set.
對此敘述沒有什麼概念,可否用比較簡單的話講解一次,謝謝...
2. We don't define quotients when the denominator is ±∞.
這個我想知道為什麼？因為我在微積分學到 x/±∞ = 0,怎在實變世界就沒定義？
謝謝你們^^
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