Difference between revisions of "User:Nik"

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=== Foreword ===
 +
I use \(Q\:/\:P\) instead of \(\widetilde{q}\:/\:\widetilde{p}\) because it's easier to write in Latex.
 +
=== Problem ===
 
Let  
 
Let  
 
\( \Phi \in C^\infty(\mathbb{R}^n) \)
 
\( \Phi \in C^\infty(\mathbb{R}^n) \)
 
have the property that the system  
 
have the property that the system  
\( p_i = \frac{\partial}{\partial q_i} \Phi (q, \widetilde{q}) \)
+
\( p_i = \frac{\partial}{\partial q_i} \Phi (q, Q \)
 
has a unique smooth solution  
 
has a unique smooth solution  
\( \widetilde{q} = \widetilde{q} (q,p) \).  
+
\( Q = Q(q,p) \).  
  
 
Define  
 
Define  
\( \widetilde{p_i}(q,p) = - \frac{\partial}{\partial \widetilde{q_i}} \Phi (q, \widetilde{q}) | _{\widetilde{q}= \widetilde{q}(q,p)} \)
+
\( P_i(q,p) = - \frac{\partial}{\partial Q_i} \Phi (q, Q) | _{Q= Q(q,p)} \)
  
 
Let \( \{\cdot,\cdot\} \) be the Poisson bracket, such that
 
Let \( \{\cdot,\cdot\} \) be the Poisson bracket, such that
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i)
 
i)
\( \{\widetilde{q_i} (q,p), \widetilde{q_j} (q,p)\} = \{\widetilde{p_i} (q,p), \widetilde{p_j} (q,p)\} = 0 \)
+
\( \{Q_i(q,p), Q_j(q,p)\} = \{P_i (q,p), P_j(q,p)\} = 0 \)
  
 
ii)
 
ii)
\( \{\widetilde{q_i} (q,p), \widetilde{p_j} (q,p)\} = \delta_{ij} \)
+
\( \{Q_i(q,p), P_j(q,p)\} = \delta_{ij} \)
  
  
 
=== Solution for i) ===
 
=== Solution for i) ===
 
=== Solution for ii) ===
 
=== Solution for ii) ===

Revision as of 10:55, 30 December 2014

Foreword

I use \(Q\:/\:P\) instead of \(\widetilde{q}\:/\:\widetilde{p}\) because it's easier to write in Latex.

Problem

Let \( \Phi \in C^\infty(\mathbb{R}^n) \) have the property that the system \( p_i = \frac{\partial}{\partial q_i} \Phi (q, Q \) has a unique smooth solution \( Q = Q(q,p) \).

Define \( P_i(q,p) = - \frac{\partial}{\partial Q_i} \Phi (q, Q) | _{Q= Q(q,p)} \)

Let \( \{\cdot,\cdot\} \) be the Poisson bracket, such that \( \{f,g\} = \sum_{j=1}^n \frac{\partial f}{\partial q_j} \frac{\partial g}{\partial p_j} - \frac{\partial f}{\partial p_j} \frac{\partial g}{\partial q_j} \)

Show that:

i) \( \{Q_i(q,p), Q_j(q,p)\} = \{P_i (q,p), P_j(q,p)\} = 0 \)

ii) \( \{Q_i(q,p), P_j(q,p)\} = \delta_{ij} \)


Solution for i)

Solution for ii)