diff --git a/src/HOL/Probability/Levy.thy b/src/HOL/Probability/Levy.thy --- a/src/HOL/Probability/Levy.thy +++ b/src/HOL/Probability/Levy.thy @@ -1,529 +1,529 @@ (* Title: HOL/Probability/Levy.thy Authors: Jeremy Avigad (CMU) *) section \The Levy inversion theorem, and the Levy continuity theorem.\ theory Levy imports Characteristic_Functions Helly_Selection Sinc_Integral begin subsection \The Levy inversion theorem\ (* Actually, this is not needed for us -- but it is useful for other purposes. (See Billingsley.) *) lemma Levy_Inversion_aux1: fixes a b :: real assumes "a \ b" shows "((\t. (iexp (-(t * a)) - iexp (-(t * b))) / (\ * t)) \ b - a) (at 0)" (is "(?F \ _) (at _)") proof - have 1: "cmod (?F t - (b - a)) \ a^2 / 2 * abs t + b^2 / 2 * abs t" if "t \ 0" for t proof - have "cmod (?F t - (b - a)) = cmod ( (iexp (-(t * a)) - (1 + \ * -(t * a))) / (\ * t) - (iexp (-(t * b)) - (1 + \ * -(t * b))) / (\ * t))" (is "_ = cmod (?one / (\ * t) - ?two / (\ * t))") using \t \ 0\ by (intro arg_cong[where f=norm]) (simp add: field_simps) also have "\ \ cmod (?one / (\ * t)) + cmod (?two / (\ * t))" by (rule norm_triangle_ineq4) also have "cmod (?one / (\ * t)) = cmod ?one / abs t" by (simp add: norm_divide norm_mult) also have "cmod (?two / (\ * t)) = cmod ?two / abs t" by (simp add: norm_divide norm_mult) also have "cmod ?one / abs t + cmod ?two / abs t \ ((- (a * t))^2 / 2) / abs t + ((- (b * t))^2 / 2) / abs t" apply (rule add_mono) apply (rule divide_right_mono) using iexp_approx1 [of "-(t * a)" 1] apply (simp add: field_simps eval_nat_numeral) apply force apply (rule divide_right_mono) using iexp_approx1 [of "-(t * b)" 1] apply (simp add: field_simps eval_nat_numeral) by force also have "\ = a^2 / 2 * abs t + b^2 / 2 * abs t" using \t \ 0\ apply (case_tac "t \ 0", simp add: field_simps power2_eq_square) using \t \ 0\ by (subst (1 2) abs_of_neg, auto simp add: field_simps power2_eq_square) finally show "cmod (?F t - (b - a)) \ a^2 / 2 * abs t + b^2 / 2 * abs t" . qed show ?thesis apply (rule LIM_zero_cancel) apply (rule tendsto_norm_zero_cancel) apply (rule real_LIM_sandwich_zero [OF _ _ 1]) apply (auto intro!: tendsto_eq_intros) done qed lemma Levy_Inversion_aux2: fixes a b t :: real assumes "a \ b" and "t \ 0" shows "cmod ((iexp (t * b) - iexp (t * a)) / (\ * t)) \ b - a" (is "?F \ _") proof - have "?F = cmod (iexp (t * a) * (iexp (t * (b - a)) - 1) / (\ * t))" using \t \ 0\ by (intro arg_cong[where f=norm]) (simp add: field_simps exp_diff exp_minus) also have "\ = cmod (iexp (t * (b - a)) - 1) / abs t" unfolding norm_divide norm_mult norm_exp_i_times using \t \ 0\ by (simp add: complex_eq_iff norm_mult) also have "\ \ abs (t * (b - a)) / abs t" using iexp_approx1 [of "t * (b - a)" 0] by (intro divide_right_mono) (auto simp add: field_simps eval_nat_numeral) also have "\ = b - a" using assms by (auto simp add: abs_mult) finally show ?thesis . qed (* TODO: refactor! *) theorem (in real_distribution) Levy_Inversion: fixes a b :: real assumes "a \ b" defines "\ \ measure M" and "\ \ char M" assumes "\ {a} = 0" and "\ {b} = 0" shows "(\T. 1 / (2 * pi) * (CLBINT t=-T..T. (iexp (-(t * a)) - iexp (-(t * b))) / (\ * t) * \ t)) \ \ {a<..b}" (is "(\T. 1 / (2 * pi) * (CLBINT t=-T..T. ?F t * \ t)) \ of_real (\ {a<..b})") proof - interpret P: pair_sigma_finite lborel M .. from bounded_Si obtain B where Bprop: "\T. abs (Si T) \ B" by auto from Bprop [of 0] have [simp]: "B \ 0" by auto let ?f = "\t x :: real. (iexp (t * (x - a)) - iexp(t * (x - b))) / (\ * t)" { fix T :: real assume "T \ 0" let ?f' = "\(t, x). indicator {-T<..R ?f t x" { fix x have 1: "complex_interval_lebesgue_integrable lborel u v (\t. ?f t x)" for u v :: real using Levy_Inversion_aux2[of "x - b" "x - a"] apply (simp add: interval_lebesgue_integrable_def set_integrable_def del: times_divide_eq_left) apply (intro integrableI_bounded_set_indicator[where B="b - a"] conjI impI) apply (auto intro!: AE_I [of _ _ "{0}"] simp: assms) done have "(CLBINT t. ?f' (t, x)) = (CLBINT t=-T..T. ?f t x)" using \T \ 0\ by (simp add: interval_lebesgue_integral_def set_lebesgue_integral_def) also have "\ = (CLBINT t=-T..(0 :: real). ?f t x) + (CLBINT t=(0 :: real)..T. ?f t x)" (is "_ = _ + ?t") using 1 by (intro interval_integral_sum[symmetric]) (simp add: min_absorb1 max_absorb2 \T \ 0\) also have "(CLBINT t=-T..(0 :: real). ?f t x) = (CLBINT t=(0::real)..T. ?f (-t) x)" by (subst interval_integral_reflect) auto also have "\ + ?t = (CLBINT t=(0::real)..T. ?f (-t) x + ?f t x)" using 1 by (intro interval_lebesgue_integral_add(2) [symmetric] interval_integrable_mirror[THEN iffD2]) simp_all also have "\ = (CLBINT t=(0::real)..T. ((iexp(t * (x - a)) - iexp (-(t * (x - a)))) - (iexp(t * (x - b)) - iexp (-(t * (x - b))))) / (\ * t))" using \T \ 0\ by (intro interval_integral_cong) (auto simp add: field_split_simps) also have "\ = (CLBINT t=(0::real)..T. complex_of_real( 2 * (sin (t * (x - a)) / t) - 2 * (sin (t * (x - b)) / t)))" using \T \ 0\ apply (intro interval_integral_cong) apply (simp add: field_simps cis.ctr Im_divide Re_divide Im_exp Re_exp complex_eq_iff) unfolding minus_diff_eq[symmetric, of "y * x" "y * a" for y a] sin_minus cos_minus apply (simp add: field_simps power2_eq_square) done also have "\ = complex_of_real (LBINT t=(0::real)..T. 2 * (sin (t * (x - a)) / t) - 2 * (sin (t * (x - b)) / t))" by (rule interval_lebesgue_integral_of_real) also have "\ = complex_of_real (2 * (sgn (x - a) * Si (T * abs (x - a)) - sgn (x - b) * Si (T * abs (x - b))))" apply (subst interval_lebesgue_integral_diff) apply (rule interval_lebesgue_integrable_mult_right, rule integrable_sinc')+ apply (subst interval_lebesgue_integral_mult_right)+ apply (simp add: zero_ereal_def[symmetric] LBINT_I0c_sin_scale_divide[OF \T \ 0\]) done finally have "(CLBINT t. ?f' (t, x)) = 2 * (sgn (x - a) * Si (T * abs (x - a)) - sgn (x - b) * Si (T * abs (x - b)))" . } note main_eq = this have "(CLBINT t=-T..T. ?F t * \ t) = (CLBINT t. (CLINT x | M. ?F t * iexp (t * x) * indicator {-T<..T \ 0\ unfolding \_def char_def interval_lebesgue_integral_def set_lebesgue_integral_def by (auto split: split_indicator intro!: Bochner_Integration.integral_cong) also have "\ = (CLBINT t. (CLINT x | M. ?f' (t, x)))" by (auto intro!: Bochner_Integration.integral_cong simp: field_simps exp_diff exp_minus split: split_indicator) also have "\ = (CLINT x | M. (CLBINT t. ?f' (t, x)))" proof (intro P.Fubini_integral [symmetric] integrableI_bounded_set [where B="b - a"]) show "emeasure (lborel \\<^sub>M M) ({- T<.. space M) < \" using \T \ 0\ by (subst emeasure_pair_measure_Times) (auto simp: ennreal_mult_less_top not_less top_unique) show "AE x\{- T<.. space M in lborel \\<^sub>M M. cmod (case x of (t, x) \ ?f' (t, x)) \ b - a" using Levy_Inversion_aux2[of "x - b" "x - a" for x] \a \ b\ by (intro AE_I [of _ _ "{0} \ UNIV"]) (force simp: emeasure_pair_measure_Times)+ qed (auto split: split_indicator split_indicator_asm) also have "\ = (CLINT x | M. (complex_of_real (2 * (sgn (x - a) * Si (T * abs (x - a)) - sgn (x - b) * Si (T * abs (x - b))))))" using main_eq by (intro Bochner_Integration.integral_cong, auto) also have "\ = complex_of_real (LINT x | M. (2 * (sgn (x - a) * Si (T * abs (x - a)) - sgn (x - b) * Si (T * abs (x - b)))))" by (rule integral_complex_of_real) finally have "(CLBINT t=-T..T. ?F t * \ t) = complex_of_real (LINT x | M. (2 * (sgn (x - a) * Si (T * abs (x - a)) - sgn (x - b) * Si (T * abs (x - b)))))" . } note main_eq2 = this have "(\T :: nat. LINT x | M. (2 * (sgn (x - a) * Si (T * abs (x - a)) - sgn (x - b) * Si (T * abs (x - b))))) \ (LINT x | M. 2 * pi * indicator {a<..b} x)" proof (rule integral_dominated_convergence [where w="\x. 4 * B"]) show "integrable M (\x. 4 * B)" by (rule integrable_const_bound [of _ "4 * B"]) auto next let ?S = "\n::nat. \x. sgn (x - a) * Si (n * \x - a\) - sgn (x - b) * Si (n * \x - b\)" { fix n x have "norm (?S n x) \ norm (sgn (x - a) * Si (n * \x - a\)) + norm (sgn (x - b) * Si (n * \x - b\))" by (rule norm_triangle_ineq4) also have "\ \ B + B" using Bprop by (intro add_mono) (auto simp: abs_mult abs_sgn_eq) finally have "norm (2 * ?S n x) \ 4 * B" by simp } then show "\n. AE x in M. norm (2 * ?S n x) \ 4 * B" by auto have "AE x in M. x \ a" "AE x in M. x \ b" using prob_eq_0[of "{a}"] prob_eq_0[of "{b}"] \\ {a} = 0\ \\ {b} = 0\ by (auto simp: \_def) then show "AE x in M. (\n. 2 * ?S n x) \ 2 * pi * indicator {a<..b} x" proof eventually_elim fix x assume x: "x \ a" "x \ b" then have "(\n. 2 * (sgn (x - a) * Si (\x - a\ * n) - sgn (x - b) * Si (\x - b\ * n))) \ 2 * (sgn (x - a) * (pi / 2) - sgn (x - b) * (pi / 2))" by (intro tendsto_intros filterlim_compose[OF Si_at_top] filterlim_tendsto_pos_mult_at_top[OF tendsto_const] filterlim_real_sequentially) auto also have "(\n. 2 * (sgn (x - a) * Si (\x - a\ * n) - sgn (x - b) * Si (\x - b\ * n))) = (\n. 2 * ?S n x)" by (auto simp: ac_simps) also have "2 * (sgn (x - a) * (pi / 2) - sgn (x - b) * (pi / 2)) = 2 * pi * indicator {a<..b} x" using x \a \ b\ by (auto split: split_indicator) finally show "(\n. 2 * ?S n x) \ 2 * pi * indicator {a<..b} x" . qed qed simp_all also have "(LINT x | M. 2 * pi * indicator {a<..b} x) = 2 * pi * \ {a<..b}" by (simp add: \_def) finally have "(\T. LINT x | M. (2 * (sgn (x - a) * Si (T * abs (x - a)) - sgn (x - b) * Si (T * abs (x - b))))) \ 2 * pi * \ {a<..b}" . with main_eq2 show ?thesis by (auto intro!: tendsto_eq_intros) qed theorem Levy_uniqueness: fixes M1 M2 :: "real measure" assumes "real_distribution M1" "real_distribution M2" and "char M1 = char M2" shows "M1 = M2" proof - interpret M1: real_distribution M1 by (rule assms) interpret M2: real_distribution M2 by (rule assms) have "countable ({x. measure M1 {x} \ 0} \ {x. measure M2 {x} \ 0})" by (intro countable_Un M2.countable_support M1.countable_support) then have count: "countable {x. measure M1 {x} \ 0 \ measure M2 {x} \ 0}" by (simp add: Un_def) have "cdf M1 = cdf M2" proof (rule ext) fix x let ?D = "\x. \cdf M1 x - cdf M2 x\" { fix \ :: real assume "\ > 0" have "(?D \ 0) at_bot" using M1.cdf_lim_at_bot M2.cdf_lim_at_bot by (intro tendsto_eq_intros) auto then have "eventually (\y. ?D y < \ / 2 \ y \ x) at_bot" using \\ > 0\ by (simp only: tendsto_iff dist_real_def diff_0_right eventually_conj eventually_le_at_bot abs_idempotent) then obtain M where "\y. y \ M \ ?D y < \ / 2" "M \ x" unfolding eventually_at_bot_linorder by auto with open_minus_countable[OF count, of "{..< M}"] obtain a where "measure M1 {a} = 0" "measure M2 {a} = 0" "a < M" "a \ x" and 1: "?D a < \ / 2" by auto have "(?D \ ?D x) (at_right x)" using M1.cdf_is_right_cont [of x] M2.cdf_is_right_cont [of x] by (intro tendsto_intros) (auto simp add: continuous_within) then have "eventually (\y. \?D y - ?D x\ < \ / 2) (at_right x)" using \\ > 0\ by (simp only: tendsto_iff dist_real_def eventually_conj eventually_at_right_less) then obtain N where "N > x" "\y. x < y \ y < N \ \?D y - ?D x\ < \ / 2" by (auto simp add: eventually_at_right[OF less_add_one]) with open_minus_countable[OF count, of "{x <..< N}"] obtain b where "x < b" "b < N" "measure M1 {b} = 0" "measure M2 {b} = 0" and 2: "\?D b - ?D x\ < \ / 2" by (auto simp: abs_minus_commute) from \a \ x\ \x < b\ have "a < b" "a \ b" by auto from \char M1 = char M2\ M1.Levy_Inversion [OF \a \ b\ \measure M1 {a} = 0\ \measure M1 {b} = 0\] M2.Levy_Inversion [OF \a \ b\ \measure M2 {a} = 0\ \measure M2 {b} = 0\] have "complex_of_real (measure M1 {a<..b}) = complex_of_real (measure M2 {a<..b})" by (intro LIMSEQ_unique) auto then have "?D a = ?D b" unfolding of_real_eq_iff M1.cdf_diff_eq [OF \a < b\, symmetric] M2.cdf_diff_eq [OF \a < b\, symmetric] by simp then have "?D x = \(?D b - ?D x) - ?D a\" by simp also have "\ \ \?D b - ?D x\ + \?D a\" by (rule abs_triangle_ineq4) also have "\ \ \ / 2 + \ / 2" using 1 2 by (intro add_mono) auto finally have "?D x \ \" by simp } then show "cdf M1 x = cdf M2 x" by (metis abs_le_zero_iff dense_ge eq_iff_diff_eq_0) qed thus ?thesis by (rule cdf_unique [OF \real_distribution M1\ \real_distribution M2\]) qed subsection \The Levy continuity theorem\ theorem levy_continuity1: fixes M :: "nat \ real measure" and M' :: "real measure" assumes "\n. real_distribution (M n)" "real_distribution M'" "weak_conv_m M M'" shows "(\n. char (M n) t) \ char M' t" unfolding char_def using assms by (rule weak_conv_imp_integral_bdd_continuous_conv) auto theorem levy_continuity: fixes M :: "nat \ real measure" and M' :: "real measure" assumes real_distr_M : "\n. real_distribution (M n)" and real_distr_M': "real_distribution M'" and char_conv: "\t. (\n. char (M n) t) \ char M' t" shows "weak_conv_m M M'" proof - interpret Mn: real_distribution "M n" for n by fact interpret M': real_distribution M' by fact have *: "\u x. u > 0 \ x \ 0 \ (CLBINT t:{-u..u}. 1 - iexp (t * x)) = 2 * (u - sin (u * x) / x)" proof - fix u :: real and x :: real assume "u > 0" and "x \ 0" hence "(CLBINT t:{-u..u}. 1 - iexp (t * x)) = (CLBINT t=-u..u. 1 - iexp (t * x))" by (subst interval_integral_Icc, auto) also have "\ = (CLBINT t=-u..0. 1 - iexp (t * x)) + (CLBINT t=0..u. 1 - iexp (t * x))" using \u > 0\ apply (subst interval_integral_sum) apply (simp add: min_absorb1 min_absorb2 max_absorb1 max_absorb2) apply (rule interval_integrable_isCont) apply auto done also have "\ = (CLBINT t=ereal 0..u. 1 - iexp (t * -x)) + (CLBINT t=ereal 0..u. 1 - iexp (t * x))" apply (subgoal_tac "0 = ereal 0", erule ssubst) by (subst interval_integral_reflect, auto) also have "\ = (LBINT t=ereal 0..u. 2 - 2 * cos (t * x))" apply (subst interval_lebesgue_integral_add (2) [symmetric]) apply ((rule interval_integrable_isCont, auto)+) [2] unfolding exp_Euler cos_of_real apply (simp add: of_real_mult interval_lebesgue_integral_of_real[symmetric]) done also have "\ = 2 * u - 2 * sin (u * x) / x" by (subst interval_lebesgue_integral_diff) (auto intro!: interval_integrable_isCont simp: interval_lebesgue_integral_of_real integral_cos [OF \x \ 0\] mult.commute[of _ x]) finally show "(CLBINT t:{-u..u}. 1 - iexp (t * x)) = 2 * (u - sin (u * x) / x)" by (simp add: field_simps) qed have main_bound: "\u n. u > 0 \ Re (CLBINT t:{-u..u}. 1 - char (M n) t) \ u * measure (M n) {x. abs x \ 2 / u}" proof - fix u :: real and n assume "u > 0" interpret P: pair_sigma_finite "M n" lborel .. (* TODO: put this in the real_distribution locale as a simp rule? *) have Mn1 [simp]: "measure (M n) UNIV = 1" by (metis Mn.prob_space Mn.space_eq_univ) (* TODO: make this automatic somehow? *) have Mn2 [simp]: "\x. complex_integrable (M n) (\t. exp (\ * complex_of_real (x * t)))" by (rule Mn.integrable_const_bound [where B = 1], auto) have Mn3: "set_integrable (M n \\<^sub>M lborel) (UNIV \ {- u..u}) (\a. 1 - exp (\ * complex_of_real (snd a * fst a)))" using \0 < u\ unfolding set_integrable_def by (intro integrableI_bounded_set_indicator [where B="2"]) (auto simp: lborel.emeasure_pair_measure_Times ennreal_mult_less_top not_less top_unique split: split_indicator intro!: order_trans [OF norm_triangle_ineq4]) have "(CLBINT t:{-u..u}. 1 - char (M n) t) = (CLBINT t:{-u..u}. (CLINT x | M n. 1 - iexp (t * x)))" unfolding char_def by (rule set_lebesgue_integral_cong, auto simp del: of_real_mult) also have "\ = (CLBINT t. (CLINT x | M n. indicator {-u..u} t *\<^sub>R (1 - iexp (t * x))))" unfolding set_lebesgue_integral_def by (rule Bochner_Integration.integral_cong) (auto split: split_indicator) also have "\ = (CLINT x | M n. (CLBINT t:{-u..u}. 1 - iexp (t * x)))" using Mn3 by (subst P.Fubini_integral) (auto simp: indicator_times split_beta' set_integrable_def set_lebesgue_integral_def) also have "\ = (CLINT x | M n. (if x = 0 then 0 else 2 * (u - sin (u * x) / x)))" using \u > 0\ by (intro Bochner_Integration.integral_cong, auto simp add: * simp del: of_real_mult) also have "\ = (LINT x | M n. (if x = 0 then 0 else 2 * (u - sin (u * x) / x)))" by (rule integral_complex_of_real) finally have "Re (CLBINT t:{-u..u}. 1 - char (M n) t) = (LINT x | M n. (if x = 0 then 0 else 2 * (u - sin (u * x) / x)))" by simp also have "\ \ (LINT x : {x. abs x \ 2 / u} | M n. u)" proof - have "complex_integrable (M n) (\x. CLBINT t:{-u..u}. 1 - iexp (snd (x, t) * fst (x, t)))" using Mn3 unfolding set_integrable_def set_lebesgue_integral_def by (intro P.integrable_fst) (simp add: indicator_times split_beta') hence "complex_integrable (M n) (\x. if x = 0 then 0 else 2 * (u - sin (u * x) / x))" using \u > 0\ unfolding set_integrable_def - by (subst integrable_cong) (auto simp add: * simp del: of_real_mult) + by (subst Bochner_Integration.integrable_cong) (auto simp add: * simp del: of_real_mult) hence **: "integrable (M n) (\x. if x = 0 then 0 else 2 * (u - sin (u * x) / x))" unfolding complex_of_real_integrable_eq . have "2 * sin x \ x" if "2 \ x" for x :: real by (rule order_trans[OF _ \2 \ x\]) auto moreover have "x \ 2 * sin x" if "x \ - 2" for x :: real by (rule order_trans[OF \x \ - 2\]) auto moreover have "x < 0 \ x \ sin x" for x :: real using sin_x_le_x[of "-x"] by simp ultimately show ?thesis using \u > 0\ unfolding set_lebesgue_integral_def by (intro integral_mono [OF _ **]) (auto simp: divide_simps sin_x_le_x mult.commute[of u] mult_neg_pos top_unique less_top[symmetric] split: split_indicator) qed also (xtrans) have "(LINT x : {x. abs x \ 2 / u} | M n. u) = u * measure (M n) {x. abs x \ 2 / u}" unfolding set_lebesgue_integral_def by (simp add: Mn.emeasure_eq_measure) finally show "Re (CLBINT t:{-u..u}. 1 - char (M n) t) \ u * measure (M n) {x. abs x \ 2 / u}" . qed have tight_aux: "\\. \ > 0 \ \a b. a < b \ (\n. 1 - \ < measure (M n) {a<..b})" proof - fix \ :: real assume "\ > 0" note M'.isCont_char [of 0] hence "\d>0. \t. abs t < d \ cmod (char M' t - 1) < \ / 4" apply (subst (asm) continuous_at_eps_delta) apply (drule_tac x = "\ / 4" in spec) using \\ > 0\ by (auto simp add: dist_real_def dist_complex_def M'.char_zero) then obtain d where "d > 0 \ (\t. (abs t < d \ cmod (char M' t - 1) < \ / 4))" .. hence d0: "d > 0" and d1: "\t. abs t < d \ cmod (char M' t - 1) < \ / 4" by auto have 1: "\x. cmod (1 - char M' x) \ 2" by (rule order_trans [OF norm_triangle_ineq4], auto simp add: M'.cmod_char_le_1) then have 2: "\u v. complex_set_integrable lborel {u..v} (\x. 1 - char M' x)" unfolding set_integrable_def by (intro integrableI_bounded_set_indicator[where B=2]) (auto simp: emeasure_lborel_Icc_eq) have 3: "\u v. integrable lborel (\x. indicat_real {u..v} x *\<^sub>R cmod (1 - char M' x))" by (intro borel_integrable_compact[OF compact_Icc] continuous_at_imp_continuous_on continuous_intros ballI M'.isCont_char continuous_intros) have "cmod (CLBINT t:{-d/2..d/2}. 1 - char M' t) \ LBINT t:{-d/2..d/2}. cmod (1 - char M' t)" unfolding set_lebesgue_integral_def using integral_norm_bound[of _ "\x. indicator {u..v} x *\<^sub>R (1 - char M' x)" for u v] by simp also have 4: "\ \ LBINT t:{-d/2..d/2}. \ / 4" unfolding set_lebesgue_integral_def apply (rule integral_mono [OF 3]) apply (simp add: emeasure_lborel_Icc_eq) apply (case_tac "x \ {-d/2..d/2}") apply auto apply (subst norm_minus_commute) apply (rule less_imp_le) apply (rule d1 [simplified]) using d0 apply auto done also from d0 4 have "\ = d * \ / 4" unfolding set_lebesgue_integral_def by simp finally have bound: "cmod (CLBINT t:{-d/2..d/2}. 1 - char M' t) \ d * \ / 4" . have "cmod (1 - char (M n) x) \ 2" for n x by (rule order_trans [OF norm_triangle_ineq4], auto simp add: Mn.cmod_char_le_1) then have "(\n. CLBINT t:{-d/2..d/2}. 1 - char (M n) t) \ (CLBINT t:{-d/2..d/2}. 1 - char M' t)" unfolding set_lebesgue_integral_def apply (intro integral_dominated_convergence[where w="\x. indicator {-d/2..d/2} x *\<^sub>R 2"]) apply (auto intro!: char_conv tendsto_intros simp: emeasure_lborel_Icc_eq split: split_indicator) done hence "eventually (\n. cmod ((CLBINT t:{-d/2..d/2}. 1 - char (M n) t) - (CLBINT t:{-d/2..d/2}. 1 - char M' t)) < d * \ / 4) sequentially" using d0 \\ > 0\ apply (subst (asm) tendsto_iff) by (subst (asm) dist_complex_def, drule spec, erule mp, auto) hence "\N. \n \ N. cmod ((CLBINT t:{-d/2..d/2}. 1 - char (M n) t) - (CLBINT t:{-d/2..d/2}. 1 - char M' t)) < d * \ / 4" by (simp add: eventually_sequentially) then obtain N where "\n\N. cmod ((CLBINT t:{- d / 2..d / 2}. 1 - char (M n) t) - (CLBINT t:{- d / 2..d / 2}. 1 - char M' t)) < d * \ / 4" .. hence N: "\n. n \ N \ cmod ((CLBINT t:{-d/2..d/2}. 1 - char (M n) t) - (CLBINT t:{-d/2..d/2}. 1 - char M' t)) < d * \ / 4" by auto { fix n assume "n \ N" have "cmod (CLBINT t:{-d/2..d/2}. 1 - char (M n) t) = cmod ((CLBINT t:{-d/2..d/2}. 1 - char (M n) t) - (CLBINT t:{-d/2..d/2}. 1 - char M' t) + (CLBINT t:{-d/2..d/2}. 1 - char M' t))" by simp also have "\ \ cmod ((CLBINT t:{-d/2..d/2}. 1 - char (M n) t) - (CLBINT t:{-d/2..d/2}. 1 - char M' t)) + cmod(CLBINT t:{-d/2..d/2}. 1 - char M' t)" by (rule norm_triangle_ineq) also have "\ < d * \ / 4 + d * \ / 4" by (rule add_less_le_mono [OF N [OF \n \ N\] bound]) also have "\ = d * \ / 2" by auto finally have "cmod (CLBINT t:{-d/2..d/2}. 1 - char (M n) t) < d * \ / 2" . hence "d * \ / 2 > Re (CLBINT t:{-d/2..d/2}. 1 - char (M n) t)" by (rule order_le_less_trans [OF complex_Re_le_cmod]) hence "d * \ / 2 > Re (CLBINT t:{-(d/2)..d/2}. 1 - char (M n) t)" (is "_ > ?lhs") by simp also have "?lhs \ (d / 2) * measure (M n) {x. abs x \ 2 / (d / 2)}" using d0 by (intro main_bound, simp) finally (xtrans) have "d * \ / 2 > (d / 2) * measure (M n) {x. abs x \ 2 / (d / 2)}" . with d0 \\ > 0\ have "\ > measure (M n) {x. abs x \ 2 / (d / 2)}" by (simp add: field_simps) hence "\ > 1 - measure (M n) (UNIV - {x. abs x \ 2 / (d / 2)})" apply (subst Mn.borel_UNIV [symmetric]) by (subst Mn.prob_compl, auto) also have "UNIV - {x. abs x \ 2 / (d / 2)} = {x. -(4 / d) < x \ x < (4 / d)}" using d0 apply (auto simp add: field_simps) (* very annoying -- this should be automatic *) apply (case_tac "x \ 0", auto simp add: field_simps) apply (subgoal_tac "0 \ x * d", arith, rule mult_nonneg_nonneg, auto) apply (case_tac "x \ 0", auto simp add: field_simps) apply (subgoal_tac "x * d \ 0", arith) apply (rule mult_nonpos_nonneg, auto) by (case_tac "x \ 0", auto simp add: field_simps) finally have "measure (M n) {x. -(4 / d) < x \ x < (4 / d)} > 1 - \" by auto } note 6 = this { fix n :: nat have *: "(UN (k :: nat). {- real k<..real k}) = UNIV" by (auto, metis leI le_less_trans less_imp_le minus_less_iff reals_Archimedean2) have "(\k. measure (M n) {- real k<..real k}) \ measure (M n) (UN (k :: nat). {- real k<..real k})" by (rule Mn.finite_Lim_measure_incseq, auto simp add: incseq_def) hence "(\k. measure (M n) {- real k<..real k}) \ 1" using Mn.prob_space unfolding * Mn.borel_UNIV by simp hence "eventually (\k. measure (M n) {- real k<..real k} > 1 - \) sequentially" apply (elim order_tendstoD (1)) using \\ > 0\ by auto } note 7 = this { fix n :: nat have "eventually (\k. \m < n. measure (M m) {- real k<..real k} > 1 - \) sequentially" (is "?P n") proof (induct n) case (Suc n) with 7[of n] show ?case by eventually_elim (auto simp add: less_Suc_eq) qed simp } note 8 = this from 8 [of N] have "\K :: nat. \k \ K. \m < Sigma_Algebra.measure (M m) {- real k<..real k}" by (auto simp add: eventually_sequentially) hence "\K :: nat. \m < Sigma_Algebra.measure (M m) {- real K<..real K}" by auto then obtain K :: nat where "\m < Sigma_Algebra.measure (M m) {- real K<..real K}" .. hence K: "\m. m < N \ 1 - \ < Sigma_Algebra.measure (M m) {- real K<..real K}" by auto let ?K' = "max K (4 / d)" have "-?K' < ?K' \ (\n. 1 - \ < measure (M n) {-?K'<..?K'})" using d0 apply auto apply (rule max.strict_coboundedI2, auto) proof - fix n show " 1 - \ < measure (M n) {- max (real K) (4 / d)<..max (real K) (4 / d)}" apply (case_tac "n < N") apply (rule order_less_le_trans) apply (erule K) apply (rule Mn.finite_measure_mono, auto) apply (rule order_less_le_trans) apply (rule 6, erule leI) by (rule Mn.finite_measure_mono, auto) qed thus "\a b. a < b \ (\n. 1 - \ < measure (M n) {a<..b})" by (intro exI) qed have tight: "tight M" by (auto simp: tight_def intro: assms tight_aux) show ?thesis proof (rule tight_subseq_weak_converge [OF real_distr_M real_distr_M' tight]) fix s \ assume s: "strict_mono (s :: nat \ nat)" assume nu: "weak_conv_m (M \ s) \" assume *: "real_distribution \" have 2: "\n. real_distribution ((M \ s) n)" unfolding comp_def by (rule assms) have 3: "\t. (\n. char ((M \ s) n) t) \ char \ t" by (intro levy_continuity1 [OF 2 * nu]) have 4: "\t. (\n. char ((M \ s) n) t) = ((\n. char (M n) t) \ s)" by (rule ext, simp) have 5: "\t. (\n. char ((M \ s) n) t) \ char M' t" by (subst 4, rule LIMSEQ_subseq_LIMSEQ [OF _ s], rule assms) hence "char \ = char M'" by (intro ext, intro LIMSEQ_unique [OF 3 5]) hence "\ = M'" by (rule Levy_uniqueness [OF * \real_distribution M'\]) thus "weak_conv_m (M \ s) M'" by (elim subst) (rule nu) qed qed end