Invariants should be well-formed formulas, that is, they should be logical statements (with a truth-value--true, of course), in the predicate calculus or rigorous English. A good invariant is a ...

Invariants and elasticity tensors play a pivotal role in the mathematical and physical description of material behaviour. By characterising properties that remain unchanged under coordinate ...

Topological materials – materials whose surface properties are very different to those in their bulk – have come to the fore in recent years and are currently revolutionizing modern condensed matter ...