Ah, I'm not referring to carbonation but establishing what the optimal temp for a given pressure or pressure for a given temp for the best fermentation.
If you are pressure fermenting to exploit higher fermentation temps for whatever reason, then for that temperature there should, in theory, be an ideal pressure, or at least a minimum pressure. And if you are looking to speed up fermentation then a max temperature for a given yeast beyond which you're not getting any further benefits regarding speed of fermentation is concerned so no point in going hotter - and possibly detrimental to go too far.
Alternatively if you don't have fermentation temp control and live in a hot country and your ambient temp might be high 20's or even into the 30 degrees, then you can establish the best pressure for the temperature the beer will be fermenting at...just would be nice to know what the 'correct' numbers are rather than guessing...just too many combinations and permutations.
I pressure fermented my last batch with S05 and selected 15 psi at 25 degrees C as a complete stab in the dark and partly informed by a question I posted on here...fermentation went pretty well. I held the beer in the fermenter post fermentation longer than I needed because I was away for a week so plenty of time for CO2 to be absorbed, albeit under carbonated for the beer style. I then soft crashed to 15 degrees for dry hop and raised pressure to 20psi to adjust carbonation to the correct level for the beer style, then 3 days dry hop and a couple of days cold crash at 3 degrees and 14 psi before kegging. Resulting beer was perfectly carbonated off the bat. So easy enough to adjust pressure for carbonation after fermentation, especially if you're dry hopping and cold crashing.
However could I have pushed fermentation temp higher? the manufacturer of the yeast doesn't provide any information on pressure fermentation on their website.
