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Propagate triangularity through matrix transpose#2174

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jessegrabowski:triangular-transpose
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Propagate triangularity through matrix transpose#2174
jessegrabowski wants to merge 1 commit into
pymc-devs:mainfrom
jessegrabowski:triangular-transpose

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@jessegrabowski jessegrabowski commented May 27, 2026

The following was not being correctly propagated:

x = assume(pt.dmatrix('x'), upper_triangular=True)
y = x.T
y.dprint(print_assumptions=True) # Expected: y is lower_triangular

This was just an oversight, so I added it.

@jessegrabowski
Propagate triangularity through matrix transpose
7de911d 
Replace the dead _dimshuffle_left_expand_dims rule (shadowed by the
default DimShuffle handler) with cross-key inference: a matrix-transpose
DimShuffle now flips lower<->upper, so downstream rewrites can see
triangular structure through .T / .mT.
@jessegrabowski jessegrabowski requested a review from ricardoV94 May 27, 2026 01:20
ricardoV94
ricardoV94 approved these changes May 27, 2026
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A bit more work but you can propagate False if the input triangularity is false (not just unknown)

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