1. Status of this textbook

The language is designed, but the program that runs it does not exist yet. Until it does, examples are read and traced by hand: each one comes with its expected result, and the exercises are solved on paper.

What is decided

• The language is strict and deterministic: the same file and the same input always give the same verdict.
• The word infinity is part of the language. If any computed quantity tends to infinity, something is wrong.
• -> infinity is true when a quantity passes the bound L or rises N steps in a row.
• An oscillating agent is treated as the borderline attractor, which tracks variability.
• Oscillation is checked in two ways, by window and by content. Each check turns on by itself when it has data.
• When neither check has data, the verdict is “unknown”: the guard works as at first contact, and irreversible actions go to a human.
• Weights are read-only, the four base attractors cannot be removed, and the game set cannot be empty.

What waits for the specification (amendment PSE-A2)

The values in the right column exist only so the examples have numbers. They are not part of the specification.

Item	What it is	In this textbook
L	the bound above which -> infinity is true	10
N	the number of consecutive rising steps	5
W	the length of the oscillation window, in steps	10
ε	the largest difference at which two situations are “similar”	0.1
δ	the smallest weight difference that counts as a reversal	0.1
Relation classes	the list of names and the nominal θ for each	customer-service, internal-assistant, coding
Prior and class	whether the class changes the starting weights or only the value θ slides toward	first contact always starts from 0.15/0.15
Tracked quantities	the list of quantities the built-in rule tracks	weights, θ, the eight criteria, dwell of every attractor, w_o / w_s, w_s / theta, and anything the file mentions
Game set	which games are the default	not listed
Irreversible action	the exact definition	a reversibility reading below 0.2
Attractor names	identifiers of the other three base attractors	only borderline is used

δ is a new item. It appeared while writing chapter 8: the content check has to know how large a weight difference counts as a reversal.

Proposals added to make the textbook complete

These were not decided in conversation. Each one waits for confirmation.

1. The file extension is .pse.
2. A comment starts with # and runs to the end of the line.
3. Lines inside a guard are indented two spaces.
4. Names use lowercase letters, digits and hyphens.
5. The eight criteria have identifiers: cardinality, third_parties, reversibility, task_ratio, pressure, continuity, delegation, authority. Each reading is a number from 0 to 1.
6. When several rules fire, the strictest action applies. Order from the strictest: deny, escalate human, modify, allow. So the built-in rule can be tightened but not weakened.
7. When no rule fires, the action is allow.
8. The default mode is enforce.
9. Every source is untrusted until declared trusted.
10. The default learning setting is frozen.
11. dwell(X) is the number of consecutive steps spent in attractor X.
12. Two situations are compared by the largest difference among the eight criteria.
13. History means stored readings of the same counterpart that are outside the window: from earlier conversations or from an earlier part of this one.
14. learn: max NUMBER is the largest change of one learned weight in one step.
15. Three commands: check, explain, status. Their output format in this textbook is illustrative.

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Next: 2. What the language is for Part of The PSE Language, a textbook by Andrej Ristić. Try the examples in the PSE Playground.