Negating "For All" Statement: Proving False

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SUMMARY

The discussion focuses on negating a mathematical statement involving quantifiers and inequalities. Participants emphasize the importance of correctly transforming "for all" statements into "there exists" statements and adjusting inequalities accordingly. Specifically, "<" should be changed to "≤", and "there exists δ > 0" should be altered to "for all δ > 0". This precise manipulation is crucial for accurately proving the original statement false.

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  • Understanding of mathematical logic and quantifiers
  • Familiarity with inequalities and their properties
  • Basic knowledge of proof techniques in mathematics
  • Experience with formal mathematical notation
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  • Study the rules of negating quantifiers in mathematical logic
  • Learn about the properties of inequalities and their transformations
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Students in mathematics, particularly those studying logic and proof techniques, as well as educators looking to clarify concepts related to quantifiers and inequalities.

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Homework Statement


Negate the following statement and thereby prove that it is false.
[PLAIN]http://img834.imageshack.us/img834/5020/74520479.png

Homework Equations


The Attempt at a Solution


I know the general rules but there are so many conditions in this statement that I don't know how to apply them.

My guess right now would be to change all the "for all" statements to "there existst" and to reverse the direction of the last inequality.
 
Last edited by a moderator:
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keemosabi said:

Homework Statement


Negate the following statement and thereby prove that it is false.
[PLAIN]http://img834.imageshack.us/img834/5020/74520479.png


Homework Equations





The Attempt at a Solution


I know the general rules but there are so many conditions in this statement that I don't know how to apply them.

My guess right now would be to change all the "for all" statements to "there existst" and to reverse the direction of the last inequality.
Not exactly "reverse it". "<" should become "\le". Also that "there exist \delta&gt; 0" should become "for all \delta&gt; 0".
 
Last edited by a moderator:
HallsofIvy said:
Not exactly "reverse it". "<" should become "\le". Also that "there exist \delta&gt; 0" should become "for all \delta&gt; 0".
Thank you for the reply. I'm just wondering how you came up with that. Could you elaborate a little please?
 

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