new metric / chart: unnecessary input heuristic (UIH)

[0xB10C]

(from closed-source 0xB10C/transactionfee.info#25)

https://x0f.org/@waxwing/109534303842306221

https://gist.github.com/AdamISZ/4551b947789d3216bacfcb7af25e029e?permalink_comment_id=2796539#gistcomment-2796539

[0xB10C]

Some chatgpt summary:

UIH (Unnecessary Input Heuristic): This is a general term for heuristics that identify when a transaction includes more inputs than necessary. The presence of unnecessary inputs can suggest attempts to obfuscate the transaction's true nature or to achieve certain privacy goals.

UIH1: This heuristic identifies transactions where one output is smaller than any input. This pattern can imply that the smaller output is a change output rather than a payment, as it's uncommon for a payment to be smaller than all inputs.

UIH2: This heuristic detects transactions where one input is larger than any output. Such a scenario suggests that the transaction might not be a standard payment, as it's unusual for a single input to exceed all outputs in value.

[0xB10C]

We need #63 for this.

[murchandamus]

UIH (Unnecessary Input Heuristic): This is a general term for heuristics that identify when a transaction includes more inputs than necessary. The presence of unnecessary inputs can suggest attempts to obfuscate the transaction's true nature or to achieve certain privacy goals.

I don’t think I’ve ever heard the term used in that context, although it doesn’t seem false per se.

UIH1: This heuristic identifies transactions where one output is smaller than any input. This pattern can imply that the smaller output is a change output rather than a payment, as it's uncommon for a payment to be smaller than all inputs.

This is how I understand UIH: it refers to a situation where one or more inputs are unnecessary to make a transaction with one of the outputs, but necessary to fund the other output. In that case, the presence of unnecessary inputs may indicate that the smaller output is the change and the larger output is the payment.

UIH2: This heuristic detects transactions where one input is larger than any output. Such a scenario suggests that the transaction might not be a standard payment, as it's unusual for a single input to exceed all outputs in value.

The second part of that point is just wrong. One input paying to two outputs is a common transaction type.