Locally constant function: Difference between revisions

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Every locally constant function from the [[real number]]s '''R''' to '''R''' is constant. But the function ''f'' from the [[rational number|rationals]] '''Q''' to '''R''', defined by ''f''(''x'') = 0 for ''x'' < [[Pi|&pi;]], and ''f''(''x'') = 1 for ''x'' > &pi;, is locally constant (here we use the fact that &pi; is [[irrational number|irrational]] and that therefore the two sets {''x''&isin;'''Q''' : ''x'' < &pi;} and {''x''&isin;'''Q''' : ''x'' > &pi;} are both [[open set|open]] in '''Q'''.
 
Generally speaking, if ''f'' : ''A'' &rarr; ''B'' is locally constant, then it is constant on any [[connected space|connected component]] of ''A''. The converse is true for [[locally connected]] spaces (where the connected components are open).
 
Further examples include the following: