Are linear lifts really linear?

[michielbdejong]

This relates to my blog post Lifts, not Payments from earlier this week - I understand that when I'm in a shop and the shopkeeper is a fellow MyCHIPs user whom I meet for the first time, I might want to do a linear lift to pay the shopkeeper within MyCHIPs.

In any case, I will need to use the shopkeeper's MyCHIPs identity to do this, (QR code or something), and I would like to get some sort of payment receipt saying "linear lift successful".

After that, or before that, the goods handover will take place in the physical world, or electronically if this is a webshop. This event stays outside of MyCHIPs and is not recorded in any way within MyCHIPs. Maybe I get a paper receipt in the physical world, or a confirmation email if it's a webshop.

In the spirit of "bringing obligations on-chain" as Cycles calls it, why don't you treat the payment receipt and the purchase receipt as chits? Then there is a linear transaction for the handover and a circular lift for the 'payment' right before or right after it, that cancels it out, and leave me and the shopkeeper at zero when the deal is completed.

[michielbdejong]

This would also change how you think about ChipNet: if Alice scans a QR code to pay in Bob's shop, is the task of ChipNet to find a linear path from Alice to Bob, or will Alice and Bob become neighbours, and is the task then formulated as finding a [set of] lift[s] that can clear the sale?

[michielbdejong]

We discussed this on Discord. Thanks for your answer!

I now understand why the functionality of a linear lift cannot be offered by an equivalent circular lift, because:

• MyCHIPs has a design principle that all tallies are denoted in CHIP
• Therefore, bringing the handover on-chain would require pricing it in CHIPs before it's clear whether or not a path exists to close the loop
• Therefore, the shopkeeper will probably be willing to accept a successful linear lift as a form of payment, but there is no way to "pencil in" the trade to see if it would loop, and then remove it if it doesn't / commit it if it does.

I'll close this issue, we can discuss it more if it comes up in another context!