+−×÷±¬∩⋂∪⋃∞ℵ∀∂∃∅∆∇⊂⊃∈∧∨≤≥/∕*∗∙√∫⊕⨁⊗⨂⊢→←↔︎≠˚ † αβγδεζηθικλμνξοπρσςτυφχψω https://cash.me/ HP Archives Riemann tensor to describe dislocation. What are the symmetries?