EXD.Preface:2 - The distinctions that change the work
The subject is what the explanation concerns. The question selects the connection sought; the purpose explains why that question matters here. The account supplies the selected claims, relations and conditions. Its expression is the prose, formula, table, diagram, demonstration or combination through which it is available. The recipient interprets and may contribute under particular preparation, access, assistance and effort conditions.
These distinctions support concrete diagnoses:
| What changes | Example | Consequence for the explanation |
|---|---|---|
| Question or purpose | Equal influence per group replaces equal weight per individual observation. | Select the corresponding calculation and label; do not diagnose the new rule as a calculation error. |
| Subject account | The relation between a group mean, its count and its sum is missing. | Supply that relation and its mathematical basis. |
| Expression | The same complete count, mean and sum claims are arranged in a table. | Compare recovery under the selected reading conditions. |
| Assistance | A hint directs attention to the unit counted by the denominator. | Preserve the help when interpreting the response. |
| Required outcome | The task changes from following today’s calculation to doing a new one next week. | Select later evidence at the required assistance and delay conditions. |
FPF C.2.8 characterizes extractable structural information for an expressed account, its expressing form and an observer under selected conditions. For an explanation, state which relations the recipient should recover, what counts as a correct reconstruction, and which preparation, operations, help, access and budget matter. The question is “How much of the selected structure can this recipient recover at these conditions?” A useful local answer can identify correctly reconstructed relations and consequential omissions. A numeric comparison needs a justified scale and comparable conditions.
This structural characterization is relational. The same text may make a connection available to an expert and leave a novice unable to reconstruct it at the same effort. Repetition may assist access or retention while introducing no new relation into the account. A familiar relation still belongs to the recoverable structure; recoverability is not a novelty score. For human recipients, attention and memory inform the use conditions and selected outcome.
Formal computational epiplexity has its own model and computational bound. Moving from it to a claim about human understanding requires a justified correspondence. The practical use of C.2.8 here does not require estimating a person’s understanding in bits. Subject warrant, extraction effort, retention, transfer, usefulness and agreement remain separately answerable.