Can You Draw a Right-Continuous Function with No Left Limit?

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Discussion Overview

The discussion revolves around the possibility of drawing a right-continuous function that lacks a left limit. Participants explore the implications of continuity in graphical representations and the definitions of right continuity.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant, Wayne, suggests that it is not possible to draw a right-continuous function without a left limit, arguing that drawing requires continuity at any point where a pen is used.
  • Another participant counters by providing the example of the function f(x) = 0 for x < 0 and f(x) = 1 for x ≥ 0, which is right-continuous at x = 0, and discusses the graphical representation using filled and open circles.
  • A later reply introduces the function f(x) = sin(1/x) for x < 0 and f(x) = 1 for x ≥ 0 as another potential example, questioning the interpretation of "draw."

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of drawing a right-continuous function without a left limit, with no consensus reached on the feasibility of such a function.

Contextual Notes

The discussion highlights ambiguities in the definitions of continuity and drawing functions, as well as the graphical conventions used to represent discontinuities.

wayneckm
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Hello all,


I am just curious about whether it is possible to DRAW a right-continuous function (without left limit). Apparently the answer is negative to me since whenever we use a pen and draw an arbitrarily short line, it must be continuous there.


Wayne
 
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I'm not sure what you mean by this.

The function y= f(x) where f(x)= 0 for x< 0, f(x)= 1 for [itex]x\ge 0[/itex] is right continuous at x= 0 and is easy to graph. Of course, there will be an ambiguity as to what happens at x= 0 unless you use the standard convention: draw a "filled circle" at the point (0, 1) to indicate that that end of the ray is included in the graph and an "open circle" at the point (0, 0) to indicate that that end of the ray is not included in the graph.
 
wayneckm said:
Hello all,


I am just curious about whether it is possible to DRAW a right-continuous function (without left limit). Apparently the answer is negative to me since whenever we use a pen and draw an arbitrarily short line, it must be continuous there.


Wayne
not sure what you mean by draw. Maybe f(x) = sin(1/x) for x<0 and f(x) =1 for x>=0
 

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