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Steamhammer versus Tyr

Here’s a curious point about Steamhammer’s ZvT and Tyr by Simon Prins. Tyr has opening learning, and center map BBS is its answer to bots which don’t defend themselves early. The BBS has always beaten Steamhammer’s mutalisk builds and lost to its zergling builds.

In the past, Tyr has tried BBS against Steamhammer and given it up after a while after losing; it concluded that a regular opening was better. Past Steamhammer versions played zergling openings 25% of the time, which was apparently enough to deter BBS even though Tyr’s slower play didn’t consistently win 75% of the time (it varied by version).

This Steamhammer version plays zergling openings ZvT 20% of the time, because the mutalisk openings are improved more (that was my thinking, at least). Tyr apparently detected the shift in game results, and now it plays BBS every game and wins 4 out of 5, a huge upswing. Can improved play can lead to worse results when it highlights remaining weaknesses for the opponent’s learning to exploit? It could also be because Tyr was updated recently. Or it could be a chance change due to the interaction of opening learning, random choice of builds by Steamhammer, and historical changes in Steamhammer’s performance.

To fix the weakness I thought of a simple adaptation, and I hope to try it out in an upcoming version. Steamhammer is prepared for early pressure versus zerg or protoss opponents, but against terran it tries to exploit the tendency of most terran bots to sit back and macro for a while. So it only has to adapt in the case of early marine pressure, as played by Tyr (with BBS) and the latest tscmoo (with an academy rush) and a number of weaker marine bots like Kruecke and KaonBot. Steamhammer should have better chances to survive if it breaks out of its prepared build when it recognizes the early pressure, and lets the strategy boss do its default thing. I doubt my simple idea is good enough by itself for all cases, but I’ll try it.

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krasi0 on :

I expect that the next generation of bot battles will be fought at the opening learning level (against the specific opponent).
It's funny how successful *random* openings turn out to be at confusing some sophisticated opening learning approaches like mine... Have you noticed SH's random opening picks to have such a devastating effect against any other opponents?

Jay Scott on :

The random openings were devastating against Ailien during the time when Ailien depended on opening learning. Ailien’s method was not the multi-arm bandit stuff that other bots use, it seemed to include inferring the enemy opening’s timing to counter it, which learned *way* faster but only worked against a fixed opening. Against the (now!) weaker learning bots like AIUR and Zia, Steamhammer would win most games anyway, but random openings allow it to play a mix of strong and weaker openings with the same effect as playing the strongest openings all the time and win nearly all games. It seems highly successful against all opening learning so far. Against bots like Iron that depend only on adaptation to the situation, the effect is to explore widely for holes (which Igor Dimitrijevic promptly fixes).

LetaBot on :

Also keep in mind builds like the 2 rax SCV all-in. My bot used to do that build.

http://wiki.teamliquid.net/starcraft/2_Rax_SCV_Allin_(vs._Zerg)

Jay Scott on :

Terran has some scary early attacks and so far no terran bots take full advantage.

Simon Prins on :

Some background from my side:

My bot hasn't been updated in a long time. The last updated that that is shown was actually me accidentally clicking the Update user info button, which apparently counts as an update.

The learning my bot uses is fairly simple: Pick a strategy, as long as you keep winning stick to it. As long as it wins at least 80% of matches also stick with it. Otherwise try the next strategy.

This is why having zergling openings 25% of time prevents my bot from sticking to the BBS strategy.

Jay Scott on :

Ha ha, so a tiny change in Steamhammer makes for a big change in Tyr's reaction!

Jay Scott on :

Also yes, changing the description counts as an update. Or even giving the impression that you may have changed the description. I found that surprising and mildly irritating.

MicroDK on :

Found two serious bugs in CombatSimulation. When fixed defense play will be much stronger! :D
1. Exclude our own static defense. Not doing this will make our units attack because they think they can beat the enemy even if the enemy is out of range of static defense. Maybe only include static defense if enemy units are in range...
2. Check for our own completed units. Not doing this will make our army think that units in being made make our army stronger and possible attack the enemy and suicide them self.
With these two changes Microwave can now beat Wuli and UAB consistently. :D

Jay Scott on :

I am getting ready to look at the new SparCraft version, so your hints are timely! I’ve been noticing a lot of battles recently where Steamhammer retreats from enemy static defense when it could instead engage enemy units that are standing unprotected.

MicroDK on :

Yah... it works both ways... maybe only include enemy static defense if your units are in range of them. Btw, how many marines can a bunker hold? Is it 5?

Jay Scott on :

Four. UAlbertaBot's original pretend bunker is pretty far off.

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