# Resource Delta¶

Resource deltas are used to reason about the total quantities of different kinds of resources in transactions. For a resource \(r\), its delta is computed as \(r.\Delta = h_{\Delta}(r.kind, r.q)\).

The function used to derive \(r.\Delta\) must have the following properties:

- For resources of the same kind \(kind\), \(h_{\Delta}\) should be
*additively homomorphic*: \(r_1.\Delta + r_2.\Delta = h_{\Delta}(kind, r_1.q + r_2.q)\) - For resources of different kinds, \(h_\Delta\) has to be
*kind-distinct*: if there exists \(kind\) and \(q\) s.t. \(h_\Delta(r_1.kind, r_1.q) + h_\Delta(r_2.kind, r_2.q) = h_\Delta(kind, q)\), it is computationally infeasible to compute \(kind\) and \(q\).

An example of a function that satisfies these properties is the Pedersen commitment scheme: it is additively homomorphic, and its kind-distinctness property comes from the discrete logarithm assumption.