How to Read This Book

Chapters are numbered from 0, like the lessons of the online course, so a reference to “Chapter 6” means the same thing in both. Each chapter opens with a question from the family and asks you to predict the answer. It then quotes the German text that answers it with an English gloss, shows the part of the model that carries it and the model’s answer, changes one fact to see what moves, and ends with what the answer gives the authority and an exercise. Solutions are at the end of the book: try the exercise first.

Three ways through

Read the book in order if you can; it is short. If you come with one job in mind, these paths keep the thread:

• Lawyers and staff of housing-benefit authorities — Chapters 0, 1, 3, 6, 7 and 8: which section decides each answer, which text applies on which day, how one decision reads step by step, where the Act leaves the decision to the Wohngeldbehörde, when another authority’s decision excludes a person, and what the model says when facts are missing.
• Programme analysts — Chapters 0, 1, 2, 3 and 4: which fact changes an answer and by how much, how the household, the rent and the income enter the formula, and how the biennial update moves a running grant.
• Developers — Chapters 0, 3, 4, 5 and 9: how a case holds facts and questions, how the formula appears in the proof, how a scenario is written against the ministry’s examples, and how a saved answer is replayed.

Every chapter opens with a short note naming what each of these readers should take from it.

Reading an answer

The model’s answers are more precise than “yes” and “no”. Every answer to a question carries one of four truth statuses — the same names in every volume of the series:

• Established — the facts and rules support the statement and do not support its opposite. The answer names the rule and the section behind it.
• Refuted — they support the opposite and do not support the statement. Not met in this book.
• Not established — they support neither. This is not zero and not a refusal: often a fact is missing, and the model names the open premise.
• Contradiction — they support both, as when two records of the file disagree on a fact. The answer keeps both, with their sources, for review instead of choosing silently.

Beside the truth status, an answer can say why there is no number, or no final answer yet:

• Requires judgment — the Act leaves a question to the authority, such as whether claiming would be abusive. The amount can be known while the claim waits; the answer names the question and the Wohngeldbehörde it is addressed to.
• Outside the model — the case is one the model does not cover, such as an owner-occupier’s Lastenzuschuss. A flag names the reason; it says nothing about the person’s entitlement.
• Past the model’s values — the date of the question lies after the last annex values this model holds. The answer names the missing values instead of carrying the old ones forward; it does not say that no values are in force.

Chapter 0 sorts the answers a housing-benefit office gives into five kinds; Chapter 8 adds records that disagree and dates past the model’s values.

Amount and claim

The book keeps two questions apart: how much the formula of § 19 gives, and whether a claim to that amount exists under §§ 19–21. The first can be established while the second is not — Chapter 6 is about exactly that.

Commands

Most chapters end with the commands behind their answers: a question asked of the case package with law ask, or a scenario file of the canon run with law test. The appendix on reproduction explains how to run them and how a saved answer is replayed: law eval evaluates the saved answer again — without the source files or a rebuild — and must give the same bytes.