chore(SetTheory/Ordinal/Exponential): redefine ordinal exponential without bsup

[vihdzp]

Ordinal.bsup is planned to be deprecated.

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[github-actions]

PR summary 4bf4d33a20

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff

+ opow
+ zero_opow_le
- opow_def
- pow
- zero_opow'

You can run this locally as follows

## summary with just the declaration names:
./scripts/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/declarations_diff.sh long <optional_commit>

The doc-module for script/declarations_diff.sh contains some details about this script.

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Decrease in tech debt: (relative, absolute) = (1.00, 0.00)

Current number	Change	Type
5095	-1	porting notes

Current commit 4bf4d33a20
Reference commit e3327a6356

You can run this locally as

./scripts/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).

[Command-Master]

lgtm. Perhaps keep opow_def, but using the new definition?

[vihdzp]

The theorems in lines 42-60 completely characterize the ordinal exponential. The definition (particularly written as it is with 1 - a) should remain a private implementation detail.