diff -r 2ecfd8985982 -r 55cc354fd2d9 src/HOL/Hyperreal/HyperDef.thy --- a/src/HOL/Hyperreal/HyperDef.thy Sat Dec 16 19:37:07 2006 +0100 +++ b/src/HOL/Hyperreal/HyperDef.thy Sat Dec 16 20:23:45 2006 +0100 @@ -8,7 +8,8 @@ header{*Construction of Hyperreals Using Ultrafilters*} theory HyperDef -imports StarClasses "../Real/Real" +imports HyperNat "../Real/Real" +uses ("hypreal_arith.ML") begin types hypreal = "real star" @@ -17,6 +18,10 @@ hypreal_of_real :: "real => real star" where "hypreal_of_real == star_of" +abbreviation + hypreal_of_hypnat :: "hypnat \ hypreal" where + "hypreal_of_hypnat \ of_hypnat" + definition omega :: hypreal where -- {*an infinite number @{text "= [<1,2,3,...>]"} *} @@ -236,4 +241,269 @@ lemma hypreal_epsilon_gt_zero: "0 < epsilon" by (simp add: hypreal_epsilon_inverse_omega) +subsection{*Absolute Value Function for the Hyperreals*} + +lemma hrabs_add_less: + "[| abs x < r; abs y < s |] ==> abs(x+y) < r + (s::hypreal)" +by (simp add: abs_if split: split_if_asm) + +lemma hrabs_less_gt_zero: "abs x < r ==> (0::hypreal) < r" +by (blast intro!: order_le_less_trans abs_ge_zero) + +lemma hrabs_disj: "abs x = (x::'a::abs_if) | abs x = -x" +by (simp add: abs_if) + +lemma hrabs_add_lemma_disj: "(y::hypreal) + - x + (y + - z) = abs (x + - z) ==> y = z | x = y" +by (simp add: abs_if split add: split_if_asm) + + +subsection{*Embedding the Naturals into the Hyperreals*} + +abbreviation + hypreal_of_nat :: "nat => hypreal" where + "hypreal_of_nat == of_nat" + +lemma SNat_eq: "Nats = {n. \N. n = hypreal_of_nat N}" +by (simp add: Nats_def image_def) + +(*------------------------------------------------------------*) +(* naturals embedded in hyperreals *) +(* is a hyperreal c.f. NS extension *) +(*------------------------------------------------------------*) + +lemma hypreal_of_nat_eq: + "hypreal_of_nat (n::nat) = hypreal_of_real (real n)" +by (simp add: real_of_nat_def) + +lemma hypreal_of_nat: + "hypreal_of_nat m = star_n (%n. real m)" +apply (fold star_of_def) +apply (simp add: real_of_nat_def) +done + +(* +FIXME: we should declare this, as for type int, but many proofs would break. +It replaces x+-y by x-y. +Addsimps [symmetric hypreal_diff_def] +*) + +use "hypreal_arith.ML" + +setup hypreal_arith_setup + + +subsection {* Exponentials on the Hyperreals *} + +lemma hpowr_0 [simp]: "r ^ 0 = (1::hypreal)" +by (rule power_0) + +lemma hpowr_Suc [simp]: "r ^ (Suc n) = (r::hypreal) * (r ^ n)" +by (rule power_Suc) + +lemma hrealpow_two: "(r::hypreal) ^ Suc (Suc 0) = r * r" +by simp + +lemma hrealpow_two_le [simp]: "(0::hypreal) \ r ^ Suc (Suc 0)" +by (auto simp add: zero_le_mult_iff) + +lemma hrealpow_two_le_add_order [simp]: + "(0::hypreal) \ u ^ Suc (Suc 0) + v ^ Suc (Suc 0)" +by (simp only: hrealpow_two_le add_nonneg_nonneg) + +lemma hrealpow_two_le_add_order2 [simp]: + "(0::hypreal) \ u ^ Suc (Suc 0) + v ^ Suc (Suc 0) + w ^ Suc (Suc 0)" +by (simp only: hrealpow_two_le add_nonneg_nonneg) + +lemma hypreal_add_nonneg_eq_0_iff: + "[| 0 \ x; 0 \ y |] ==> (x+y = 0) = (x = 0 & y = (0::hypreal))" +by arith + + +text{*FIXME: DELETE THESE*} +lemma hypreal_three_squares_add_zero_iff: + "(x*x + y*y + z*z = 0) = (x = 0 & y = 0 & z = (0::hypreal))" +apply (simp only: zero_le_square add_nonneg_nonneg hypreal_add_nonneg_eq_0_iff, auto) +done + +lemma hrealpow_three_squares_add_zero_iff [simp]: + "(x ^ Suc (Suc 0) + y ^ Suc (Suc 0) + z ^ Suc (Suc 0) = (0::hypreal)) = + (x = 0 & y = 0 & z = 0)" +by (simp only: hypreal_three_squares_add_zero_iff hrealpow_two) + +(*FIXME: This and RealPow.abs_realpow_two should be replaced by an abstract + result proved in Ring_and_Field*) +lemma hrabs_hrealpow_two [simp]: + "abs(x ^ Suc (Suc 0)) = (x::hypreal) ^ Suc (Suc 0)" +by (simp add: abs_mult) + +lemma two_hrealpow_ge_one [simp]: "(1::hypreal) \ 2 ^ n" +by (insert power_increasing [of 0 n "2::hypreal"], simp) + +lemma two_hrealpow_gt [simp]: "hypreal_of_nat n < 2 ^ n" +apply (induct_tac "n") +apply (auto simp add: left_distrib) +apply (cut_tac n = n in two_hrealpow_ge_one, arith) +done + +lemma hrealpow: + "star_n X ^ m = star_n (%n. (X n::real) ^ m)" +apply (induct_tac "m") +apply (auto simp add: star_n_one_num star_n_mult power_0) +done + +lemma hrealpow_sum_square_expand: + "(x + (y::hypreal)) ^ Suc (Suc 0) = + x ^ Suc (Suc 0) + y ^ Suc (Suc 0) + (hypreal_of_nat (Suc (Suc 0)))*x*y" +by (simp add: right_distrib left_distrib) + +lemma power_hypreal_of_real_number_of: + "(number_of v :: hypreal) ^ n = hypreal_of_real ((number_of v) ^ n)" +by simp +declare power_hypreal_of_real_number_of [of _ "number_of w", standard, simp] +(* +lemma hrealpow_HFinite: + fixes x :: "'a::{real_normed_algebra,recpower} star" + shows "x \ HFinite ==> x ^ n \ HFinite" +apply (induct_tac "n") +apply (auto simp add: power_Suc intro: HFinite_mult) +done +*) + +subsection{*Powers with Hypernatural Exponents*} + +definition + (* hypernatural powers of hyperreals *) + pow :: "['a::power star, nat star] \ 'a star" (infixr "pow" 80) where + hyperpow_def [transfer_unfold]: + "R pow N = ( *f2* op ^) R N" + +lemma hyperpow: "star_n X pow star_n Y = star_n (%n. X n ^ Y n)" +by (simp add: hyperpow_def starfun2_star_n) + +lemma hyperpow_zero [simp]: + "\n. (0::'a::{recpower,semiring_0} star) pow (n + (1::hypnat)) = 0" +by transfer simp + +lemma hyperpow_not_zero: + "\r n. r \ (0::'a::{recpower,field} star) ==> r pow n \ 0" +by transfer (rule field_power_not_zero) + +lemma hyperpow_inverse: + "\r n. r \ (0::'a::{recpower,division_by_zero,field} star) + \ inverse (r pow n) = (inverse r) pow n" +by transfer (rule power_inverse) + +lemma hyperpow_hrabs: + "\r n. abs (r::'a::{recpower,ordered_idom} star) pow n = abs (r pow n)" +by transfer (rule power_abs [symmetric]) + +lemma hyperpow_add: + "\r n m. (r::'a::recpower star) pow (n + m) = (r pow n) * (r pow m)" +by transfer (rule power_add) + +lemma hyperpow_one [simp]: + "\r. (r::'a::recpower star) pow (1::hypnat) = r" +by transfer (rule power_one_right) + +lemma hyperpow_two: + "\r. (r::'a::recpower star) pow ((1::hypnat) + (1::hypnat)) = r * r" +by transfer (simp add: power_Suc) + +lemma hyperpow_gt_zero: + "\r n. (0::'a::{recpower,ordered_semidom} star) < r \ 0 < r pow n" +by transfer (rule zero_less_power) + +lemma hyperpow_ge_zero: + "\r n. (0::'a::{recpower,ordered_semidom} star) \ r \ 0 \ r pow n" +by transfer (rule zero_le_power) + +lemma hyperpow_le: + "\x y n. \(0::'a::{recpower,ordered_semidom} star) < x; x \ y\ + \ x pow n \ y pow n" +by transfer (rule power_mono [OF _ order_less_imp_le]) + +lemma hyperpow_eq_one [simp]: + "\n. 1 pow n = (1::'a::recpower star)" +by transfer (rule power_one) + +lemma hrabs_hyperpow_minus_one [simp]: + "\n. abs(-1 pow n) = (1::'a::{number_ring,recpower,ordered_idom} star)" +by transfer (rule abs_power_minus_one) + +lemma hyperpow_mult: + "\r s n. (r * s::'a::{comm_monoid_mult,recpower} star) pow n + = (r pow n) * (s pow n)" +by transfer (rule power_mult_distrib) + +lemma hyperpow_two_le [simp]: + "(0::'a::{recpower,ordered_ring_strict} star) \ r pow (1 + 1)" +by (auto simp add: hyperpow_two zero_le_mult_iff) + +lemma hrabs_hyperpow_two [simp]: + "abs(x pow (1 + 1)) = + (x::'a::{recpower,ordered_ring_strict} star) pow (1 + 1)" +by (simp only: abs_of_nonneg hyperpow_two_le) + +lemma hyperpow_two_hrabs [simp]: + "abs(x::'a::{recpower,ordered_idom} star) pow (1 + 1) = x pow (1 + 1)" +by (simp add: hyperpow_hrabs) + +text{*The precondition could be weakened to @{term "0\x"}*} +lemma hypreal_mult_less_mono: + "[| u u*x < v* y" + by (simp add: Ring_and_Field.mult_strict_mono order_less_imp_le) + +lemma hyperpow_two_gt_one: + "\r::'a::{recpower,ordered_semidom} star. 1 < r \ 1 < r pow (1 + 1)" +by transfer (simp add: power_gt1) + +lemma hyperpow_two_ge_one: + "\r::'a::{recpower,ordered_semidom} star. 1 \ r \ 1 \ r pow (1 + 1)" +by transfer (simp add: one_le_power) + +lemma two_hyperpow_ge_one [simp]: "(1::hypreal) \ 2 pow n" +apply (rule_tac y = "1 pow n" in order_trans) +apply (rule_tac [2] hyperpow_le, auto) +done + +lemma hyperpow_minus_one2 [simp]: + "!!n. -1 pow ((1 + 1)*n) = (1::hypreal)" +by transfer (subst power_mult, simp) + +lemma hyperpow_less_le: + "!!r n N. [|(0::hypreal) \ r; r \ 1; n < N|] ==> r pow N \ r pow n" +by transfer (rule power_decreasing [OF order_less_imp_le]) + +lemma hyperpow_SHNat_le: + "[| 0 \ r; r \ (1::hypreal); N \ HNatInfinite |] + ==> ALL n: Nats. r pow N \ r pow n" +by (auto intro!: hyperpow_less_le simp add: HNatInfinite_iff) + +lemma hyperpow_realpow: + "(hypreal_of_real r) pow (hypnat_of_nat n) = hypreal_of_real (r ^ n)" +by transfer (rule refl) + +lemma hyperpow_SReal [simp]: + "(hypreal_of_real r) pow (hypnat_of_nat n) \ Reals" +by (simp add: hyperpow_def Reals_eq_Standard) + +lemma hyperpow_zero_HNatInfinite [simp]: + "N \ HNatInfinite ==> (0::hypreal) pow N = 0" +by (drule HNatInfinite_is_Suc, auto) + +lemma hyperpow_le_le: + "[| (0::hypreal) \ r; r \ 1; n \ N |] ==> r pow N \ r pow n" +apply (drule order_le_less [of n, THEN iffD1]) +apply (auto intro: hyperpow_less_le) +done + +lemma hyperpow_Suc_le_self2: + "[| (0::hypreal) \ r; r < 1 |] ==> r pow (n + (1::hypnat)) \ r" +apply (drule_tac n = " (1::hypnat) " in hyperpow_le_le) +apply auto +done + +lemma hyperpow_hypnat_of_nat: "\x. x pow hypnat_of_nat n = x ^ n" +by transfer (rule refl) + end