The bots

A position is worth its centres, and almost nothing else: units are how you
get them and are worth nothing in themselves. Every other term is a small
correction on that one fact.

Orders are a greedy plan taken in order of what is worth most, with a second
unit put behind the first when the prize is worth two units -- a bot that
never doubles up is not playing this game. Agreements are applied after the
plan rather than as a constraint on it, on purpose: the plan has to know what
it is giving up before it can decide whether the promise is worth keeping.

Three things the tests taught it. It garrisons a threatened centre it is
already standing on, because scoring only moves had it defending Berlin by
marching the Munich garrison there. It never shoves at its own countryman,
which has no strength and wastes two units. And the price of breaking a
promise is how far it trusts the partner, not how far the partner trusts it
-- the other way round gives a power that has been lied to four times a high
cost of retaliating, because it has been scrupulous and is still well thought
of, which is exactly backwards.

Every decision comes back as a sentence. When a power turns on you it says
what the province was worth and what it thought you were worth, because being
betrayed should be infuriating rather than mysterious.

README.md

@@ -117,9 +117,31 @@ surprises:
 Sections H, I and J -- retreating and the winter -- have engine code but no
 harness yet; their cases are shaped differently and need one.
 
+## The bots
+
+`src/game/evaluate.ts` prices a position and `src/game/bot.ts` plays it.
+Everything a power does comes out of two numbers, and they are deliberately
+few: when a power turns on you, you are entitled to know what it thought it
+was getting and be furious about the price rather than confused by it.
+`chooseOrders` returns its reasoning as a list of sentences for exactly that.
+
+Centres are the only thing that counts. Units are how you get them and are
+worth nothing in themselves -- a power with eight units and four centres is
+losing, and will have four units by the winter.
+
+Two things the tests had to teach it. It garrisons a threatened centre it is
+already standing on, because scoring only *moves* had it defending Berlin by
+marching the Munich garrison there -- abandoning one centre to save another
+of identical value. And it never shoves at its own countryman, which has no
+strength at all and is two units wasting a turn on each other.
+
+The price of breaking a promise is **how far this power trusts the partner**,
+not how far the partner trusts it. Pricing it the other way round gives a
+power that has been lied to four times a high cost of retaliating, because it
+has been scrupulous itself and is still well thought of, which is exactly
+backwards. An ally who has already betrayed you is worth nothing to protect.
+
 ## Still to build
 
-- the adjudicator, and the DATC cases that prove it
-- the press: offers, memory, and the arithmetic of betrayal
-- the bots' actual play
-- the map, the orders, the music
+- proposals: bots opening a negotiation rather than only answering one
+- the map, the orders, the music, the battle sound, the four endings