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Project-declaredLean 4.24.0-rc1 · mathlib@aad26963

Da concat det run cnt2

Automata.da_concat_det_run_cnt2

Plain-language statement

The second state component of M1.Concat acc1 M2 always has at least one inactive copy of M2 available.

Exact Lean statement

theorem da_concat_det_run_cnt2 (as : Stream' A) (n : ℕ) :
    ∃ i, ((M1.Concat acc1 M2).DetRun as n).2 i = none

Formal artifact

Lean source

Canonical source
Full Lean sourceLean 4
theorem da_concat_det_run_cnt2 (as : Stream' A) (n : ) :     i, ((M1.Concat acc1 M2).DetRun as n).2 i = none := by  induction' n with n h_ind  · use 0 ; simp [DA.DetRun, DA.Concat]  let s_n := (M1.Concat acc1 M2).DetRun as n  obtain i, h_i := h_ind  rcases Classical.em ( j, j  i  s_n.2 j = none) with h_none | h_some  · obtain j, h_ne, h_j := h_none    simp [s_n] at h_j    wlog h : i < j generalizing i j with h'    · exact h' j h_j i (Ne.symm h_ne) h_i (by fin_omega)    use j ; simp [DA.DetRun, da_concat_next_2, h_j]    intro _ ; use i  · simp [ne_none_iff_isSome] at h_some    have h1 : {j | (s_n.2 j).isSome} = {i}ᶜ := by ext j ; simp ; grind    have h2 : {j | (s_n.2 j).isSome}.ncard = Nat.card M2.State + 1 := by      have h_sum := ncard_add_ncard_compl {i} ; simp at h_sum      rw [h1] ; omega    obtain j1, j2, h_ne, s2, h_j1, h_j2 := option_some_pigeonhole s_n.2 (by omega)    wlog h : j1 < j2 generalizing j1 j2 with h'    · exact h' j2 j1 (Ne.symm h_ne) h_j2 h_j1 (by fin_omega)    simp [s_n] at h_j1 h_j2    use j2 ; simp [DA.DetRun, da_concat_next_2, h_j2]    use j1 ; simp [h, h_j1]
Project
Automata Theory
License
Apache-2.0
Commit
f196548710ce
Source
AutomataTheory/Automata/DetConcat.lean:125-148

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Related declarations

Project-declaredLean 4.24.0-rc1

Acc lang congr

acc_lang_congr

Plain-language statement

The language accepted by c.toDA with a unique accepting state s is exactly the equivalence class of s.

automata theoryformal languagescomputer science

Source project: Automata Theory

Person-level attribution pending.

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Project-declaredLean 4.24.0-rc1

Acc lang concat e

Automata.acc_lang_concat_e

Plain-language statement

The language of the concatenation NA that is accepted by M0's accepting states is the language accepted by M0.

automata theoryformal languagescomputer science

Source project: Automata Theory

Person-level attribution pending.

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Project-declaredLean 4.24.0-rc1

Acc lang concat ne

Automata.acc_lang_concat_ne

Plain-language statement

The language of the concatenation NA that is accepted by M1's accepting states is the language accepted by M0 concatenated with the language accepted by M1 minus the empty word.

automata theoryformal languagescomputer science

Source project: Automata Theory

Person-level attribution pending.

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