user124647: I've read the paper "Optimally Reliable & Cheap Payment Flows on the Lightning Network" by Rene Pickhardt & Stefan Richter and I'm tempted to assume the answer to my question, but I still have some nagging doubts.  So, I'll ask here.
It's clear that setting base fees to zero helps the pathfinding system because base fees don't scale linearly - they're zero when the value transferred is zero, and a fixed non-zero amount when the value transferred is non-zero.
What's not clear is whether setting a minimum HTLC will affect the pathfinding.   Some people have pointed out concerns that with a base fee of zero, the routing fee can be rounded down to zero on small payments.  That'd allow someone to spam a larger payment through as a series of tiny payments at no cost.  Setting a sufficiently sized min HTLC (sufficient for your fee rate so that all routes are at least 1 msat) can avoid this, but obviously at the expense of no longer being able to route arbitrarily small amounts.
My main question is therefore simply: does setting a minimum HTLC value influence the pathfinding in Pickhardt payments at all?
Related question: If yes, in what ways?  Is it scale related?  To get an idea of this: How harmful to the overall system would it be if everyone had small (e.g. 10sat) min HTLC settings?  How about larger (e.g. an unrealistic value like 10000sat)?

user176: In theory, it isn't clear to me yet if finding a min-cost flow is any harder when there are minimum flows. In practice, it's not at all a problem as long as the min HTLC size is small. That's because we calculate the optimum flows with a global minimum flow size (resolution) anyway, and typical values for that are 10k-100ksat. At the moment, the maximum observed min-HTLC-size in the network is 50ksat, and even that isn't a problem. For smaller sizes, the optimal flow will always be a single path anyway.
With regards to effects on the network, that's more speculative, but obviously, if everybody used min-HTLC-size, very small payments wouldn't work anymore.

124647: <p>I've read the paper &quot;<a href="https://arxiv.org/pdf/2107.05322.pdf" rel="nofollow noreferrer">Optimally Reliable &amp; Cheap Payment Flows on the Lightning Network</a>&quot; by Rene Pickhardt &amp; Stefan Richter and I'm tempted to assume the answer to my question, but I still have some nagging doubts.  So, I'll ask here.</p>
<p>It's clear that setting base fees to zero helps the pathfinding system because base fees don't scale linearly - they're zero when the value transferred is zero, and a fixed non-zero amount when the value transferred is non-zero.</p>
<p>What's not clear is whether setting a minimum HTLC will affect the pathfinding.   Some people have pointed out concerns that with a base fee of zero, the routing fee can be rounded down to zero on small payments.  That'd allow someone to spam a larger payment through as a series of tiny payments at no cost.  Setting a sufficiently sized min HTLC (sufficient for your fee rate so that all routes are at least 1 msat) can avoid this, but obviously at the expense of no longer being able to route arbitrarily small amounts.</p>
<p>My main question is therefore simply: does setting a minimum HTLC value influence the pathfinding in Pickhardt payments at all?</p>
<p>Related question: If yes, in what ways?  Is it scale related?  To get an idea of this: How harmful to the overall system would it be if everyone had small (e.g. 10sat) min HTLC settings?  How about larger (e.g. an unrealistic value like 10000sat)?</p>
 176: <p>In theory, it isn't clear to me yet if finding a min-cost flow is any harder when there are minimum flows. In practice, it's not at all a problem as long as the min HTLC size is small. That's because we calculate the optimum flows with a global minimum flow size (resolution) anyway, and typical values for that are 10k-100ksat. At the moment, the maximum observed min-HTLC-size in the network is 50ksat, and even that isn't a problem. For smaller sizes, the optimal flow will always be a single path anyway.</p>
<p>With regards to effects on the network, that's more speculative, but obviously, if everybody used min-HTLC-size, very small payments wouldn't work anymore.</p>
