Can you solve the Kronecker identity?

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Discussion Overview

The discussion revolves around the Kronecker identity, specifically the expression for the partial derivative of one variable with respect to another, represented as \(\frac{\partial x_{i}}{\partial x_{j}} = \delta_{ij}\). Participants explore its meaning and implications in the context of mathematical notation and definitions.

Discussion Character

  • Technical explanation

Main Points Raised

  • Some participants clarify that \(\frac{\partial x_{i}}{\partial x_{j}} = \delta_{ij}\) indicates that the partial derivative is 1 when \(i = j\) and 0 when \(i \neq j.
  • Others elaborate that if \(i = j\), the partial derivative of \(x_i\) with respect to itself is 1, while if \(i\) does not equal \(j\), and assuming \(x_i\) is independent of \(x_j\), the derivative is 0.
  • It is noted that the Kronecker Delta is defined to reflect these same conditions, reinforcing the relationship between the partial derivative and the delta function.

Areas of Agreement / Disagreement

Participants generally agree on the interpretation of the Kronecker identity and its implications regarding partial derivatives, though the discussion does not delve into deeper implications or applications.

Contextual Notes

The discussion does not address any potential limitations or assumptions regarding the variables involved or the context in which the identity is applied.

spaghetti3451
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I'd like to see how many people can explain this identity:

[tex]\frac{\partialx_{i}}{\partialx_{j}} = \delta_{ij}[/tex]
 
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[tex] \frac{\partial x_{i}}{\partial x_{j}} = \delta_{ij}[/tex]
 
is what i meant.
 
It means that ∂xi / ∂xj is 1 if i=j and 0 if i≠j. In general δi,j is 1 if i=j and 0 if i≠j.
 
If i=j, then the partial derivative of xi with respect to itself is 1. If i does not equal j, then assuming that xi is not dependent on xj, then the partial derivative of xi with respect to xj is 0. The Kronecker Delta is defined such that the same holds true (when i=j, it's equal to 1, and otherwise it's 0).
 

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