Are PST necessary for a good HCE?

[KhepriChess]

In my mind, and I could be very wrong here, it seems like it would be possible to encourage good play (through a good evaluation) by coding in the various ideas for pieces and patterns. I get that PST implicitly do this, but don't they also add a level of arbitrariness?

Is it just that PST are an easy way to add those things (rather than a potentially longer eval function to individually add various patterns, etc.) and the search function will ruling out any quirks introduced by potential arbitrary square scores?

Could an effective HCE eval be done without PSTs?

[syzygy]

In my mind, and I could be very wrong here, it seems like it would be possible to encourage good play (through a good evaluation) by coding in the various ideas for pieces and patterns. I get that PST implicitly do this, but don't they also add a level of arbitrariness?

Is it just that PST are an easy way to add those things (rather than a potentially longer eval function to individually add various patterns, etc.) and the search function will ruling out any quirks introduced by potential arbitrary square scores?

Could an effective HCE eval be done without PSTs?

You could implement knight mobility by looking up a mobility value in an array indexed by the knight's current square. Oh, we have invented PSTs

PSTs are evaluation patterns like any other evaluation pattern.

[smatovic]

...some people pointed out that PSTs with Texel Tuning Method are a kind of SLP NN with backpropagation, the precursor of NNUE so to speak.

--
Srdja

[abulmo2]

Olithink is a relatively strong program with a mobility based evaluation and no PST, so you can avoid PST and still have a competitive engine. Note that Olithink's evaluation is 100% hand crafted; whereas strong PST based engines, like PeSTO or my more modest engine Dumb, are automatically tuned by computer in a very similar way done for NNUE evaluations.

[Mike Sherwin]

The PST can also be algorithmically created before each search like is done in RomiChess. Just do it better than I did.