Remove EinExprs dependency (#327)

## Summary
- **Breaking**: removes the `alg = "einexpr"` contraction sequence
optimizer. Downstream users should switch to one of `"optimal"`,
`"greedy"`, `"tree_sa"`, `"sa_bipartite"`, or `"kahypar_bipartite"` (all
still dispatched through the OMEinsumContractionOrders extension).
- Deletes the `ITensorNetworksEinExprsExt` weak-dep extension and drops
`EinExprs` from both the root and `test/` Project.toml.
- Removes the `alg = "einexpr"` cases (and the commented-out
KaHyPar/einexpr block) from `test/test_contraction_sequence.jl`.
- Bumps the version to `0.16.0` (minor bump for a pre-1.0 breaking
change) and updates pinned `ITensorNetworks` compat in `test/`, `docs/`,
and `examples/` Project.toml accordingly.

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: mtfishman

Project.toml

@@ -1,6 +1,6 @@
 name = "ITensorNetworks"
 uuid = "2919e153-833c-4bdc-8836-1ea460a35fc7"
-version = "0.15.27"
+version = "0.16.0"
 authors = ["Matthew Fishman <mfishman@flatironinstitute.org>, Joseph Tindall <jtindall@flatironinstitute.org> and contributors"]
 
 [workspace]
@@ -39,14 +39,12 @@ TimerOutputs = "a759f4b9-e2f1-59dc-863e-4aeb61b1ea8f"
 TupleTools = "9d95972d-f1c8-5527-a6e0-b4b365fa01f6"
 
 [weakdeps]
-EinExprs = "b1794770-133b-4de1-afb4-526377e9f4c5"
 GraphsFlows = "06909019-6f44-4949-96fc-b9d9aaa02889"
 OMEinsumContractionOrders = "6f22d1fd-8eed-4bb7-9776-e7d684900715"
 Observers = "338f10d5-c7f1-4033-a7d1-f9dec39bcaa0"
 TensorOperations = "6aa20fa7-93e2-5fca-9bc0-fbd0db3c71a2"
 
 [extensions]
-ITensorNetworksEinExprsExt = "EinExprs"
 ITensorNetworksGraphsFlowsExt = "GraphsFlows"
 ITensorNetworksOMEinsumContractionOrdersExt = "OMEinsumContractionOrders"
 ITensorNetworksObserversExt = "Observers"
@@ -64,7 +62,6 @@ DataStructures = "0.18"
 Dictionaries = "0.4"
 Distributions = "0.25.86"
 DocStringExtensions = "0.9"
-EinExprs = "0.6.4, 0.7"
 Graphs = "1.8"
 GraphsFlows = "0.1.1"
 ITensors = "0.7, 0.8, 0.9"

docs/Project.toml

@@ -16,7 +16,7 @@ path = ".."
 Documenter = "1.10"
 Graphs = "1"
 ITensorFormatter = "0.2.27"
-ITensorNetworks = "0.15"
+ITensorNetworks = "0.16"
 ITensors = "0.9"
 Literate = "2.20.1"
 NamedGraphs = "0.8.2"

examples/Project.toml

@@ -5,4 +5,4 @@ ITensorNetworks = "2919e153-833c-4bdc-8836-1ea460a35fc7"
 path = ".."
 
 [compat]
-ITensorNetworks = "0.15"
+ITensorNetworks = "0.16"

ext/ITensorNetworksEinExprsExt/ITensorNetworksEinExprsExt.jl

@@ -6,7 +6,6 @@ Compat = "34da2185-b29b-5c13-b0c7-acf172513d20"
 DataGraphs = "b5a273c3-7e6c-41f6-98bd-8d7f1525a36a"
 Dictionaries = "85a47980-9c8c-11e8-2b9f-f7ca1fa99fb4"
 Distributions = "31c24e10-a181-5473-b8eb-7969acd0382f"
-EinExprs = "b1794770-133b-4de1-afb4-526377e9f4c5"
 Glob = "c27321d9-0574-5035-807b-f59d2c89b15c"
 Graphs = "86223c79-3864-5bf0-83f7-82e725a168b6"
 GraphsFlows = "06909019-6f44-4949-96fc-b9d9aaa02889"
@@ -43,12 +42,11 @@ Compat = "4.16"
 DataGraphs = "0.2.13"
 Dictionaries = "0.4.4"
 Distributions = "0.25.118"
-EinExprs = "0.6.8, 0.7"
 Glob = "1.3.1"
 Graphs = "1.12"
 GraphsFlows = "0.1.1"
 ITensorMPS = "0.3.6"
-ITensorNetworks = "0.15"
+ITensorNetworks = "0.16"
 ITensorPkgSkeleton = "0.3.42"
 ITensors = "0.7, 0.8, 0.9"
 KrylovKit = "0.8, 0.9, 0.10"

test/Project.toml

@@ -1,5 +1,4 @@
 @eval module $(gensym())
-using EinExprs: Exhaustive, Greedy
 using ITensorNetworks:
     contraction_sequence, norm_sqr_network, random_tensornetwork, siteinds
 using ITensors: ITensors, contract
@@ -25,18 +24,9 @@ using Test: @test, @testset
         res_tree_sa = contract(tn; sequence = seq_tree_sa)[]
         seq_sa_bipartite = contraction_sequence(tn; alg = "sa_bipartite")
         res_sa_bipartite = contract(tn; sequence = seq_sa_bipartite)[]
-        seq_einexprs_exhaustive = contraction_sequence(
-            tn; alg = "einexpr", optimizer = Exhaustive()
-        )
-        res_einexprs_exhaustive = contract(tn; sequence = seq_einexprs_exhaustive)[]
-        seq_einexprs_greedy =
-            contraction_sequence(tn; alg = "einexpr", optimizer = Greedy())
-        res_einexprs_greedy = contract(tn; sequence = seq_einexprs_exhaustive)[]
         @test res_greedy ≈ res_optimal
         @test res_tree_sa ≈ res_optimal
         @test res_sa_bipartite ≈ res_optimal
-        @test res_einexprs_exhaustive ≈ res_optimal
-        @test res_einexprs_greedy ≈ res_optimal
 
         if !Sys.iswindows()
             # KaHyPar doesn't work on Windows
@@ -50,10 +40,6 @@ using Test: @test, @testset
             Pkg.rm("KaHyPar"; io = devnull)
             res_kahypar_bipartite = contract(tn; sequence = seq_kahypar_bipartite)[]
             @test res_optimal ≈ res_kahypar_bipartite
-            #These tests were leading to CI issues that need to be investigated
-            # seq_einexprs_kahypar = contraction_sequence(tn; alg="einexpr", optimizer=HyPar())
-            # res_einexprs_kahypar = contract(tn; sequence=seq_einexprs_kahypar)[]
-            # @test res_einexprs_kahypar ≈ res_optimal
         end
     end
 end