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Fix constDF case in Stratified induction - #15

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Fix constDF case in Stratified induction#15
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Summary

This removes one sorry in Lean4Lean/Experimental/Stratified.lean, in the constDF case of IsDefEq.induction1.

This is the typed/stratified analogue of #14. The proof binds the recursive induction hypotheses explicitly in the constDF case pattern and uses the Γ-level induction hypothesis in reverse through hdf.

A first attempt with an explicit universe argument failed because it over-constrained the type index. Letting Lean infer the .defeq universe argument resolves the index.

Verification

Checked locally:

lake build Lean4Lean.Experimental.Stratified
lake build

Both passed.

Note: the repository still contains unrelated existing sorrys in other files; this PR only removes the target sorry in Stratified.lean.

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Fix constDF case in Stratified induction by heathsanchez · Pull Request #15 · digama0/lean4lean · GitHub
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Fix constDF case in Stratified induction - #15
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Fix constDF case in Stratified induction#15
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Summary
This removes one sorry in Lean4Lean/Experimental/Stratified.lean, in the constDF case of IsDefEq.induction1.
This is the typed/stratified analogue of #14. The proof binds the recursive induction hypotheses explicitly in the constDF case pattern and uses the Γ-level induction hypothesis in reverse through hdf.
A first attempt with an explicit universe argument failed because it over-constrained the type index. Letting Lean infer the .defeq universe argument resolves the index.
Verification
Checked locally:
lake build Lean4Lean.Experimental.Stratified
lake build

Both passed.
Note: the repository still contains unrelated existing sorrys in other files; this PR only removes the target sorry in Stratified.lean.
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Fix constDF case in Stratified induction by heathsanchez · Pull Request #15 · digama0/lean4lean · GitHub
Skip to content
Fix constDF case in Stratified induction - #15
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heathsanchez wants to merge 1 commit into
digama0:masterfrom 
heathsanchez:sorrydb-fix-stratified-constdf-typed
Open
Fix constDF case in Stratified induction#15
heathsanchez wants to merge 1 commit into
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heathsanchez:sorrydb-fix-stratified-constdf-typed
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@heathsanchez
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Jul 5, 2026

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Summary
This removes one sorry in Lean4Lean/Experimental/Stratified.lean, in the constDF case of IsDefEq.induction1.
This is the typed/stratified analogue of #14. The proof binds the recursive induction hypotheses explicitly in the constDF case pattern and uses the Γ-level induction hypothesis in reverse through hdf.
A first attempt with an explicit universe argument failed because it over-constrained the type index. Letting Lean infer the .defeq universe argument resolves the index.
Verification
Checked locally:
lake build Lean4Lean.Experimental.Stratified
lake build

Both passed.
Note: the repository still contains unrelated existing sorrys in other files; this PR only removes the target sorry in Stratified.lean.
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Fix constDF case in Stratified induction by heathsanchez · Pull Request #15 · digama0/lean4lean · GitHub
Skip to content
Fix constDF case in Stratified induction - #15
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heathsanchez wants to merge 1 commit into
digama0:masterfrom 
heathsanchez:sorrydb-fix-stratified-constdf-typed
Open
Fix constDF case in Stratified induction#15
heathsanchez wants to merge 1 commit into
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heathsanchez:sorrydb-fix-stratified-constdf-typed
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@heathsanchez
@heathsanchezheathsanchez
commented
Jul 5, 2026

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Summary
This removes one sorry in Lean4Lean/Experimental/Stratified.lean, in the constDF case of IsDefEq.induction1.
This is the typed/stratified analogue of #14. The proof binds the recursive induction hypotheses explicitly in the constDF case pattern and uses the Γ-level induction hypothesis in reverse through hdf.
A first attempt with an explicit universe argument failed because it over-constrained the type index. Letting Lean infer the .defeq universe argument resolves the index.
Verification
Checked locally:
lake build Lean4Lean.Experimental.Stratified
lake build

Both passed.
Note: the repository still contains unrelated existing sorrys in other files; this PR only removes the target sorry in Stratified.lean.
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, 'i');
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Fix constDF case in Stratified induction by heathsanchez · Pull Request #15 · digama0/lean4lean · GitHub
Skip to content
Fix constDF case in Stratified induction - #15
Open
heathsanchez wants to merge 1 commit into
digama0:masterfrom 
heathsanchez:sorrydb-fix-stratified-constdf-typed
Open
Fix constDF case in Stratified induction#15
heathsanchez wants to merge 1 commit into
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heathsanchez:sorrydb-fix-stratified-constdf-typed
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@heathsanchez
@heathsanchezheathsanchez
commented
Jul 5, 2026

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Summary
This removes one sorry in Lean4Lean/Experimental/Stratified.lean, in the constDF case of IsDefEq.induction1.
This is the typed/stratified analogue of #14. The proof binds the recursive induction hypotheses explicitly in the constDF case pattern and uses the Γ-level induction hypothesis in reverse through hdf.
A first attempt with an explicit universe argument failed because it over-constrained the type index. Letting Lean infer the .defeq universe argument resolves the index.
Verification
Checked locally:
lake build Lean4Lean.Experimental.Stratified
lake build

Both passed.
Note: the repository still contains unrelated existing sorrys in other files; this PR only removes the target sorry in Stratified.lean.
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, 'i');
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var __m = "*";
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Fix constDF case in Stratified induction by heathsanchez · Pull Request #15 · digama0/lean4lean · GitHub
Skip to content
Fix constDF case in Stratified induction - #15
Open
heathsanchez wants to merge 1 commit into
digama0:masterfrom 
heathsanchez:sorrydb-fix-stratified-constdf-typed
Open
Fix constDF case in Stratified induction#15
heathsanchez wants to merge 1 commit into
digama0:masterfrom 
heathsanchez:sorrydb-fix-stratified-constdf-typed
Conversation
@heathsanchez
@heathsanchezheathsanchez
commented
Jul 5, 2026

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Summary
This removes one sorry in Lean4Lean/Experimental/Stratified.lean, in the constDF case of IsDefEq.induction1.
This is the typed/stratified analogue of #14. The proof binds the recursive induction hypotheses explicitly in the constDF case pattern and uses the Γ-level induction hypothesis in reverse through hdf.
A first attempt with an explicit universe argument failed because it over-constrained the type index. Letting Lean infer the .defeq universe argument resolves the index.
Verification
Checked locally:
lake build Lean4Lean.Experimental.Stratified
lake build

Both passed.
Note: the repository still contains unrelated existing sorrys in other files; this PR only removes the target sorry in Stratified.lean.
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, 'i');
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try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Fix constDF case in Stratified induction by heathsanchez · Pull Request #15 · digama0/lean4lean · GitHub
Skip to content
Fix constDF case in Stratified induction - #15
Open
heathsanchez wants to merge 1 commit into
digama0:masterfrom 
heathsanchez:sorrydb-fix-stratified-constdf-typed
Open
Fix constDF case in Stratified induction#15
heathsanchez wants to merge 1 commit into
digama0:masterfrom 
heathsanchez:sorrydb-fix-stratified-constdf-typed
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@heathsanchez
@heathsanchezheathsanchez
commented
Jul 5, 2026

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Summary
This removes one sorry in Lean4Lean/Experimental/Stratified.lean, in the constDF case of IsDefEq.induction1.
This is the typed/stratified analogue of #14. The proof binds the recursive induction hypotheses explicitly in the constDF case pattern and uses the Γ-level induction hypothesis in reverse through hdf.
A first attempt with an explicit universe argument failed because it over-constrained the type index. Letting Lean infer the .defeq universe argument resolves the index.
Verification
Checked locally:
lake build Lean4Lean.Experimental.Stratified
lake build

Both passed.
Note: the repository still contains unrelated existing sorrys in other files; this PR only removes the target sorry in Stratified.lean.
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, 'i');
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Fix constDF case in Stratified induction by heathsanchez · Pull Request #15 · digama0/lean4lean · GitHub
Skip to content
Fix constDF case in Stratified induction - #15
Open
heathsanchez wants to merge 1 commit into
digama0:masterfrom 
heathsanchez:sorrydb-fix-stratified-constdf-typed
Open
Fix constDF case in Stratified induction#15
heathsanchez wants to merge 1 commit into
digama0:masterfrom 
heathsanchez:sorrydb-fix-stratified-constdf-typed
Conversation
@heathsanchez
@heathsanchezheathsanchez
commented
Jul 5, 2026

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Summary
This removes one sorry in Lean4Lean/Experimental/Stratified.lean, in the constDF case of IsDefEq.induction1.
This is the typed/stratified analogue of #14. The proof binds the recursive induction hypotheses explicitly in the constDF case pattern and uses the Γ-level induction hypothesis in reverse through hdf.
A first attempt with an explicit universe argument failed because it over-constrained the type index. Letting Lean infer the .defeq universe argument resolves the index.
Verification
Checked locally:
lake build Lean4Lean.Experimental.Stratified
lake build

Both passed.
Note: the repository still contains unrelated existing sorrys in other files; this PR only removes the target sorry in Stratified.lean.
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