3. [Continuity equations](https://en.wikipedia.org/wiki/Continuity_equation) and general [**conservation laws**](https://en.wikipedia.org/wiki/Conservation_law).
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4. Conservation principles for extensities: [**invariants**](https://en.wikipedia.org/wiki/Invariant_(physics)) / [**symmetries**](https://en.wikipedia.org/wiki/Symmetry_(physics)).
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3. [Conservation](/MSP/Materials/model-intro/Conservation%20of%20extensities) of **extensities**.
