feat: a decided variable becomes a supplied number, so a subproblem is a call on the whole model

[FBumann]

Prompt: Start with #303 and the cut formula
Draft PRs, stacked

Note

The following content was generated by AI.

What this changes

spec.fix(*names) turns each named variable into a parameter with the same name. A masked variable keeps its meaning: each read outside a sum is proven guarded, masked at its row, or refused with the reader named. Closes #303. Stacked on #747.

Rules, evidence, gates, open questions

The rewrite

• The variable becomes a parameter over the same dims. binary and integer become int; continuous becomes float. The description is kept.
• Its bounds, and a binary's 0 and 1, become the assumption <name>_within_bounds, under the variable's where:.
• A constraint that named only fixed variables becomes an assumption under its own name, with its where: and description. The loader refuses such a row, and its message names this rewrite.
• A set or a curve that names the variable refuses the fix. spec.expand().fix(...) works.
• All names are fixed in one rewrite, which is validated once. fix('a').fix('b') equals fix('a', 'b').

The masked variable (what #249 found, re-made on current main)

A variable with where: and absence: undefined does not exist outside its mask, and a row reading it there is not built. A parameter reads 0 there, so the row stands: p <= cap * avail becomes p <= 0. #249 answered with coverage: masked, which main no longer has. This PR proves each read instead:

• Inside sum, sum(by=) or sum_back, an absent summand and a 0 one give the same sum.
• A read under a mask that holds every conjunct of the variable's mask (the row's where:, or a case's when) is guarded.
• An unguarded read directly in a constraint whose frame carries the variable's dims gets the mask added to that constraint's where:.
• A read through shift or at, or in an unguarded case, is refused, and the message names the reader.

Evidence

examples/pypsa.yaml on main at 22cdebd, fixing the seven *_nom_ext capacities and the three *_n_mod module counts:

• No constraint gains a where:. Every pointwise read already stands under ..._extendable.
• 34 rows that only limited capacity become assumptions: the _ext_*_nom_lower/upper, _nom_set, _p_nom_modularity, Carrier_growth_limit and GlobalConstraint_*_expansion_* families.
• separability['snapshot'].linking_columns goes from 13 variables to the three CVaR columns, which the risk measure spans across snapshots by design.

Before #736 folded the stochastic and multi-period classes into this file, the same test fixed six variables and the snapshot axis linked no column.

specsolve's examples/benders/ monolith: fix('cap') gives an LP whose snapshot axis links no column. specsolve ships that subproblem as a second file, sub.yaml, with cap renamed to cap_hat.

Guards

Guard deleted	Fails
a binary or integer becomes int	2 domain rows
masked reads are checked	4
absence: zero needs no check	zero-outside-the-mask-is-what-a-missing-row-reads
a sum absorbs the absence	7
a guarded read is left alone	4
a read through a shift is refused	through-a-shift
a read in an unguarded case is refused	in-a-case-its-mask-does-not-guard
settled rows become assumptions	2, pypsa included
a set refuses	1
a curve refuses	1
a name given twice refuses	1

Gates

• pixi run lint: pass.
• pixi run test: 2714 passed, on the merge of main at 22cdebd.
• docs-build and compile-tex were not run in the session (network). CI runs both.

Open, for review

• A reported expression that reads the masked variable is not guarded: where it read nothing, it now reads 0. It is documented in the docstring, not refused.
• dual(c) of a constraint that becomes an assumption stops resolving; the reload names it.
• The mask is added as (<row where>) AND (<variable where>), text on text. It is proven only where the variable's dims are in the row's frame.

Why

#303: a hand-written fix in a driver is wrong twice and silently, and two drivers would decide it differently.

🤖 Generated with Claude Code

https://claude.ai/code/session_01CvcU9JRnsinc9e9syvVcHS

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Generated by Claude Code

[read-the-docs-community]

Documentation build overview

📚 mathspec | 🛠️ Build #34821178 | 📁 Comparing 707f0b9 against latest (0efbf59)

  🔍 Preview build  

60 files changed · + 32 added · ± 24 modified · - 4 deleted

+ Added

• several-files/index.html
• examples/library/index.html
• howto/compare/index.html
• howto/compose/index.html
• examples/library/composed/index.html
• examples/library/generator/index.html
• examples/library/load/index.html
• examples/library/surface/index.html
• examples/pypsa/carrier/index.html
• examples/pypsa/cost/index.html
• and 22 more...

± Modified

• index.html
• changelog/index.html
• examples/index.html
• about/limits/index.html
• examples/commitment/index.html
• examples/dispatch/index.html
• examples/operators/index.html
• examples/pypsa/index.html
• examples/pypsa_linearized_uc/index.html
• howto/pin-a-variable/index.html
• and 14 more...

- Deleted

• examples/pypsa_losses/index.html
• examples/pypsa_multi_period/index.html
• examples/pypsa_quadratic/index.html
• examples/pypsa_stochastic/index.html

[FBumann]

Prompt: "Then port 749 as a stacked pr onto it and close 748 and 749 as superseded"

Note

The following content was generated by AI.

Superseded by #824, which carries this diff onto main without the #746 → #747 base. #824 also fixes a bug: two masked variables fixed in one call kept only the second mask.

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Generated by Claude Code