ITensorNetwork type fixes and other minor refactors. by jack-dunham · Pull Request #175 · ITensor/ITensorNetworksNext.jl

jack-dunham · 2026-09-08T14:48:30Z

Fixes and cleanups to the ITensorNetwork type, the BP message cache, and gate application.

add_edge!/rem_edge! on ITensorNetwork return false instead of throwing.
dimnamevertices returns an empty set for a name the network does not hold.
New operator_support(tn, op): the vertices carrying the operator's input index names. An absent name contributes no vertex; a name on several vertices throws.
Tensor assignment checks index names before mutating, so a rejected assignment no longer leaves dimname_vertices and the underlying graph half-updated.
finalize_substate! takes both subsolve and solve objects as arguments.
bethe_free_energy's duplicated log-sum factored into sumlog.

ITensorBot · 2026-09-08T14:50:41Z

Your PR no longer requires formatting changes. Thank you for your contribution!

codecov · 2026-09-08T14:52:17Z

Codecov Report

❌ Patch coverage is 98.41270% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 86.68%. Comparing base (5119963) to head (1ed3f96).

Files with missing lines	Patch %	Lines
src/tensornetwork.jl	96.42%	1 Missing ⚠️

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+ Misses         97       94       -3

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mtfishman · 2026-09-14T15:39:37Z

    return tn
 end
+
+function supportof(tn::AbstractGraph, op::ITensorOperator)


I think maybe I'd call this operator_support, just to not make it sound so generic, i.e. we don't know what the "scope" of this function will be. Also, what about constraining to tn::AbstractITensorNetwork?

I worry about constraining such functions as then they no longer "just work" on e.g. wrappers that do not subtype AbstractITensorNetwork.

As for the name, I have no strong opinions. I have been drafting the ITensorNetworkOperator object, where this function would also have a method for. I don't know if that changes your opinion (although operator_support would still work in that case).

"wrappers that do not subtype AbstractITensorNetwork": We could always generalize when we have those cases (or maybe you have one already?). "I don't know if that changes your opinion": I think that still fits, i.e. I think operator_support would assume some structure of the operator, like it has input and output indices and you are specifically matching against input indices. We could always generalize the name as the use cases generalize.

There is no specific case. It is more of a case of me deciding to choose the default to be AbstractGraph when it does not introduce type piracy or ambiguity after having to change this multiple times to accommodate QuotientView.

Happy to change the name.

mtfishman · 2026-09-14T15:53:00Z

 # PERF: fast lookup compared to `AbstractITensorNetwork` fallback.
-dimnamevertices(tn::ITensorNetwork, name) = tn.dimname_vertices[name]
+function dimnamevertices(tn::ITensorNetwork, name)
+    return get(tn.dimname_vertices, name, Set{vertextype(tn)}())


I think this makes more sense, but was this inspired by a particular use case?

It is for consistency with the fallback method (which returns an empty set).

…alse instead of erroring This is inline with the `Graphs` behaviour.

… not in dictionary This is now consistant with the fallback defn of `dimnamevertices`. would error previously.

… on a tensor network.

…setting tensors

Avoids some minor code duplication.

…an solve.

Fix imports in `apply_operators.jl`

…patch Convention from `MatrixAlgebraKit`.

mtfishman · 2026-09-14T21:26:31Z


+# (log|∏terms|, sign(∏terms))
+function sumlogabs(terms)
+    T = typeof(first(terms))


I think eltype(terms) is better, since it would work when terms is empty.

The problem is that real(eltype(terms)) fails if the eltype of terms is Any.

It might be better to just pass in T directly, and have a default if T <: Any.

…type from param

mtfishman · 2026-09-15T13:19:19Z

+# give element type `Any`; collecting the values instead picks up the type they actually have.
 function vertex_scalars(factors, messages, vertices)
-    return map(v -> vertex_scalar(factors, messages, v), vertices)
+    return [vertex_scalar(factors, messages, v) for v in vertices]


I think an issue with this version is that it now returns a Vector instead of a Dictionary, I think a Dictionary is a bit nicer since it preserves which scalar is associated with which vertex. Maybe we could do dictionary(vertices, [vertex_scalar(factors, messages, v) for v in vertices])?

Ah, I see, I guess before it would have output whatever map infers from the input, so if vertices was a Vector it would output a Vector while if it was Indices it would output a Dictionary... A bit tricky to try to reproduce that behavior (which I think is kind of nice...). Maybe we could define our own narrow_map(f, x) function:

narrow_map(f, v) = map(f, v) narrow_map(f, v::AbstactIndices) = dictionary(v, [f(x) for x in v])

The problem with map(f, v) is that the element type of the resulting collection ends up as Any. It is a consequence of the element type of ITensor not being parameterized. The comprehension automatically infers the element type at runtime, hence why I switched to that as it then means that sumlogabs gets a subtype of Number as its element type so real(T) works.

mtfishman · 2026-09-16T20:36:55Z

 end
+
+function operator_support(tn::AbstractGraph, op::ITensorOperator)
+    support = Set{vertextype(tn)}()


Maybe use Dictionaries.Indices?

mtfishman · 2026-09-16T20:44:48Z

-function set!_tensornetwork(tn::ITensorNetwork, vertex, tensor)
-    newinds = dimnames(tensor)
+function update_tensornetwork_metadata!(tn, vertex, tensor)
+    oldnames = isassigned(tn, vertex) ? dimnames(tn[vertex]) : Set()


Suggested change

oldnames = isassigned(tn, vertex) ? dimnames(tn[vertex]) : Set()

oldnames = isassigned(tn, vertex) ? dimnames(tn[vertex]) : Set{dimnametype(tn)}()

jack-dunham force-pushed the jd/tensornetwork-type-updates branch 2 times, most recently from dee5559 to faa56ff Compare September 9, 2026 18:12

mtfishman reviewed Sep 14, 2026

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Comment thread src/beliefpropagation/messagecache.jl Outdated

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Comment thread src/tensornetwork.jl Outdated

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jack-dunham added 15 commits September 14, 2026 14:42

add_edge! and rem_edge! on the ITensorNetwork type now return f…

35e491e

…alse instead of erroring This is inline with the `Graphs` behaviour.

dimnamevertices for ITensorNetwork now returns empty set if index…

25b18fa

… not in dictionary This is now consistant with the fallback defn of `dimnamevertices`. would error previously.

New function supportof that gives the vertex support of an operator…

5dc2aeb

… on a tensor network.

Refactor ITensorNetwork topology functions; add index precheck for …

9e57b58

…setting tensors

Refactor sum of log scalars into own function.

fc2b71f

Avoids some minor code duplication.

The finalize_substate function now dispatches on subsolve rather th…

0c59060

…an solve.

Upgrade to ITensorBase v0.13

01b76ee

Fix imports in `apply_operators.jl`

Fix rename of vs to vertices in function body.

511703e

Function supportof can now return an empty set; add tests.

d9db486

Rename function supportof to operator_support.

7ca1852

Fix variable names that refer to inds instead of the correct names.

5b277f3

Refactor and rename sum_log_scalars to sumlog.

112b78c

Replace check_incoming_dimnames with check_input and function dis…

0bc2b8f

…patch Convention from `MatrixAlgebraKit`.

Formatting

4482a48

finalize_substate! now takes both solve and subsolve objects.

48534f9

jack-dunham force-pushed the jd/tensornetwork-type-updates branch from 7225dab to 48534f9 Compare September 14, 2026 18:56

mtfishman reviewed Sep 14, 2026

View reviewed changes

Fix type stabilty in vertex/edge_scalars; sumlogabs now infers el…

1ed3f96

…type from param

mtfishman reviewed Sep 15, 2026

View reviewed changes

mtfishman reviewed Sep 16, 2026

View reviewed changes

	oldnames = isassigned(tn, vertex) ? dimnames(tn[vertex]) : Set()
	oldnames = isassigned(tn, vertex) ? dimnames(tn[vertex]) : Set{dimnametype(tn)}()

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