Show Me Your Map
by Timothy J. Harland
A map-maker’s guide

Piece 3 of 3 — Chapters 11–12
From the Author’s Portal · showyourmap.com
Free for weary travelers. E UNUM PLURIBUM.

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CHAPTER 11

What Has to Remain the Same?
A representation can change shape without losing everything that made it useful.
The question is what actually has to survive the change.

Different Form, Same Relationship
Imagine two tools built for different jobs.
They look different.
They operate differently.
Their environments are different.
But both may still follow the same basic relationship:
   input → control → output
The surface changes.
The relationship remains.
That difference matters.

Strip Away the Extras
When something continues to work across several situations, some of its features may
turn out to be incidental.
Change the setting.
Change the example.
Remove a detail.
Then ask:
   What can I change without changing everything?
If the relationship still holds, that detail may belong to the form rather than the
structure.
If removing it changes the relationship itself, it may be carrying more weight than we
realized.

A Candidate Kernel
If a relationship continues to work while the surrounding details change, the
remaining structure deserves attention.

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But persistence alone is not enough.
Something may appear essential simply because we never changed it.
That makes it a candidate.
Not a conclusion.

Move the Anchor
Once the viable changes around an apparent invariant have been explored, the
invariant itself becomes testable.
Change it. If practical, substitute something else into the same position.
If safe and feasible, remove it provisionally. Preserve as much of the surrounding
comparison as practical.
Then observe what happens in each state.
If the relevant relationship remains materially unchanged after substitution or
provisional removal, the original invariant was probably not the kernel.
It may have been familiar, persistent, convenient, or correlated.
But it was not necessary.
If changing or removing the invariant materially changes the relationship, we have
stronger evidence that it contributes something load-bearing.
If removal makes the system worse, the suspected problem may also have been limiting
the magnitude of another problem.
And sometimes the contribution does not belong entirely to the invariant itself.
It may belong to the interface through which that invariant acts - or to the
relationship between them.
Change the interface and compare again.
The difference helps reveal whether the important structure belongs to the element,
the connection, or the relationship between them.

What Must Remain
The question is no longer simply:
    What keeps appearing?
It becomes:
   What must remain for this relationship to keep working?
The kernel is not what stays the same because we kept it fixed.
It is the smallest necessary structure that remains load-bearing as the surrounding
form, apparent anchors, and interfaces are challenged.

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The Relationship May Be the Kernel
Sometimes changing either node leaves the system intact.
Changing the connection between them does not.
In those cases, the kernel is not the component, person, role, or anchor.
    It is the relationship that must remain.
Eventually, even the anchor gets audited.
And once we have a structure that appears to survive those tests, there is still one
problem.
Conditions change.
New information appears.
The terrain moves.
   What do we do when the map changes again?

                                            24

CHAPTER 12

What Do We Do When the Map Changes Again?
A useful map is not a finished map.
Conditions change.
New information appears.
Old assumptions stop holding.
When that happens, we do not necessarily start over.
We find where the map stopped matching the terrain.
Keep what still works.
Revise what does not.
Leave unresolved what the evidence cannot yet support.
A map does not remain useful because it remains unchanged.
It remains useful because it can change without pretending it was ever the terrain.
Eventually every useful map reaches something it did not contain.
   What if?

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This page has been left intentionally blank
       for cartographical purposes.

  Today’s model is tomorrow’s baseline.