theorem
proved
RCLCombiner_zero_separatelyAdditive
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IndisputableMonolith.Foundation.BranchSelection on GitHub at line 130.
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127/-- For `c = 0`, the RCL combiner is the additive combiner
128`P(u, v) = 2u + 2v`, separately additive with `p(u) = 2u` and
129`q(v) = 2v`. -/
130theorem RCLCombiner_zero_separatelyAdditive :
131 SeparatelyAdditive (RCLCombiner 0) := by
132 refine ⟨fun u => 2 * u, fun v => 2 * v, ?_⟩
133 intro u v
134 unfold RCLCombiner
135 ring
136
137/-- For `c ≠ 0`, the RCL combiner has nonvanishing interaction defect
138at the test point `(1, 1)`. -/
139theorem RCLCombiner_nonzero_couples (c : ℝ) (hc : c ≠ 0) :
140 interactionDefect (RCLCombiner c) 1 1 ≠ 0 := by
141 rw [interactionDefect_RCLCombiner]
142 simpa using hc
143
144/-- **The RCL combiner is a coupling combiner iff `c ≠ 0`.** -/
145theorem RCLCombiner_isCoupling_iff (c : ℝ) :
146 IsCouplingCombiner (RCLCombiner c) ↔ c ≠ 0 := by
147 rw [isCouplingCombiner_iff_interactionDefect_nonzero]
148 constructor
149 · rintro ⟨u, v, huv⟩
150 intro hc
151 apply huv
152 rw [interactionDefect_RCLCombiner, hc]
153 ring
154 · intro hc
155 exact ⟨1, 1, RCLCombiner_nonzero_couples c hc⟩
156
157/-! ## Branch Selection Theorem -/
158
159/-- **Branch selection by non-degeneracy.**
160