Solving Inequality: Get Help with (Uw-UL)<a-B

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Discussion Overview

The discussion revolves around understanding an inequality presented in a paper, specifically the expression (Uw-UL)

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about the derivation of the inequality (Uw-UL)
  • Another participant states that the inequality holds if and only if α > β, suggesting that reversing the inequality would imply α < β.
  • A participant asks for a step-by-step derivation of the last equation under the assumption that α > β.
  • One participant provides a derivation starting from a modified inequality and notes that if α - β > 0, they can multiply through by 2(α - β) to arrive at Uw - UL < α - β.
  • Another participant questions whether α and β are reversed, proposing a different form of the inequality involving (β - α).
  • A participant confirms the reversal was done to eliminate a leading negative term, indicating a different approach to the problem.

Areas of Agreement / Disagreement

Participants generally agree on the condition α > β for the inequality to hold, but there is disagreement regarding the correct formulation of the inequality and the implications of reversing α and β.

Contextual Notes

The discussion includes assumptions about the relationships between the variables and the conditions under which the inequalities are valid. There are unresolved steps in the derivation that may depend on specific definitions or interpretations of the terms involved.

martyfarty
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Hi, I am reading a paper and in this equation is given.

View attachment 6477

I don't quite follow how they end up with the last (Uw-UL)<a-B. If I do it myself I get the inequality sign wrong.

Any help?

Thx
 

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Welcome martyfarty,

The inequality holds if and only if $\alpha > \beta$. If you had the inequality reversed, then perhaps you had $\alpha < \beta$.
 
Indeed \alpha > \beta is true. How would you step by step come to the last equation given that \alpha > \beta?
 
Let's first subtract $$\frac{1}{2}$$ from both sides:

$$\frac{\left(U^W-U^L\right)}{2(\alpha-\beta)}<\frac{1}{2}$$

If $\alpha-\beta>0$, then we may multiply through by $2(\alpha-\beta)$ to get:

$$U^W-U^L<\alpha-\beta$$
 
MarkFL said:
Let's first subtract $$\frac{1}{2}$$ from both sides:

$$\frac{\left(U^W-U^L\right)}{2(\alpha-\beta)}<\frac{1}{2}$$

If $\alpha-\beta>0$, then we may multiply through by $2(\alpha-\beta)$ to get:

$$U^W-U^L<\alpha-\beta$$

However, $$\alpha$$ and $$\beta$$ are reversed right? Like this

$$\frac{\left(U^W-U^L\right)}{2(\beta-\alpha)}<\frac{1}{2}$$
 
martyfarty said:
However, $$\alpha$$ and $$\beta$$ are reversed right? Like this

$$\frac{\left(U^W-U^L\right)}{2(\beta-\alpha)}<\frac{1}{2}$$

No, I reversed them to get rid of the leading negative for that term. :D
 
MarkFL said:
No, I reversed them to get rid of the leading negative for that term. :D

Okay wow, that option did not even cross my mind haha. Thanks for your help!
 

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