Wolfram Language Paclet Repository
Community-contributed installable additions to the Wolfram Language
Wolfram`TensorNetworks`
TensorNetworkGraphQ  |
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A valid tensor-network graph is a in which every vertex carries two annotations: a (the underlying array) and an (a duplicate-free list of or labels).
"Tensor"
"Index"
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Two consistency rules must hold across the vertex annotations: each tensor's rank equals the length of its list, and the sum of all tensor ranks equals the count of distinct indices across all vertices.
"Index"
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Edges in the graph may carry tags identifying which output and input slots are contracted along that edge; focuses on the vertex annotations and does not separately validate edge tags.
{,}
src
i
tgt
j
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When the second argument is , a failing check prints one of four diagnostic message tags: (vertices not annotated with tensors), (indices not a duplicate-free list of / heads), (tensor ranks and indices incompatible), and (edges not tagged with indices). Both vertex-annotation checks are exercised in current builds; and are reserved for stricter checks added in future revisions.
msg1
msg2
msg3
msg4
msg1
msg4
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is the graph-form sibling of : the latter tests […] expressions, while tests the annotated produced by .
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Downstream functions including , , , and are guarded by , so they remain unevaluated on an invalid graph rather than producing a wrong answer.
Examples
(7)
Basic Examples
(1)
Build a valid annotated tensor-network graph and test it:
In[1]:=
SeedRandom[42];g=
["MPS"[4,2,2]];
 | ToTensorNetworkGraph |
 | RandomTensorNetwork |
In[2]:=
 | TensorNetworkGraphQ |
Out[2]=
True
A plain Graph carries no "Tensor" or "Index" annotations, so the predicate returns False:
In[3]:=
| TensorNetworkGraphQ |
Out[3]=
False
Pass True as a second argument to print the first failing check on a malformed graph:
In[4]:=
| TensorNetworkGraphQ |
Out[4]=
False
Scope
(4)
Applications
(1)
Properties & Relations
(1)
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