:: A Representation of Integers by Binary Arithmetics and Addition of Integers
:: by Hisayoshi Kunimune and Yatsuka Nakamura
::
:: Received January 30, 2003
:: Copyright (c) 2003-2021 Association of Mizar Users

theorem Th1: :: BINARI_4:1

for m being Nat st m > 0 holds
m * 2 >= m + 1

proof end;

theorem Th2: :: BINARI_4:2

for m being Nat holds 2 to_power m >= m

proof end;

theorem :: BINARI_4:3

for m being Nat holds (0* m) + (0* m) = 0* m

proof end;

theorem Th4: :: BINARI_4:4

for k, m, l being Nat st k <= l & l <= m & not k = l holds
( k + 1 <= l & l <= m )

proof end;

theorem Th5: :: BINARI_4:5

for n being non zero Nat
for x, y being Tuple of n, BOOLEAN st x = 0* n & y = 0* n holds
carry (x,y) = 0* n

proof end;

theorem :: BINARI_4:6

for n being non zero Nat
for x, y being Tuple of n, BOOLEAN st x = 0* n & y = 0* n holds
x + y = 0* n

proof end;

theorem :: BINARI_4:7

for n being non zero Nat
for F being Tuple of n, BOOLEAN st F = 0* n holds
Intval F = 0

proof end;

theorem Th8: :: BINARI_4:8

for k, l, m being Nat st l + m <= k - 1 holds
( l < k & m < k )

proof end;

theorem Th9: :: BINARI_4:9

for g, h, i being Integer st g <= h + i & h < 0 & i < 0 holds
( g < h & g < i )

proof end;

theorem Th10: :: BINARI_4:10

for n being non zero Nat
for l, m being Nat st l + m <= (2 to_power n) - 1 holds
add_ovfl ((n -BinarySequence l),(n -BinarySequence m)) = FALSE

proof end;

theorem Th11: :: BINARI_4:11

for n being non zero Nat
for l, m being Nat st l + m <= (2 to_power n) - 1 holds
Absval ((n -BinarySequence l) + (n -BinarySequence m)) = l + m

proof end;

theorem Th12: :: BINARI_4:12

for n being non zero Nat
for z being Tuple of n, BOOLEAN st z /. n = TRUE holds
Absval z >= 2 to_power (n -' 1)

proof end;

theorem Th13: :: BINARI_4:13

for n being non zero Nat
for l, m being Nat st l + m <= (2 to_power (n -' 1)) - 1 holds
(carry ((n -BinarySequence l),(n -BinarySequence m))) /. n = FALSE

proof end;

theorem Th14: :: BINARI_4:14

for l, m being Nat
for n being non zero Nat st l + m <= (2 to_power (n -' 1)) - 1 holds
Intval ((n -BinarySequence l) + (n -BinarySequence m)) = l + m

proof end;

theorem Th15: :: BINARI_4:15

for z being Tuple of 1, BOOLEAN st z = <*TRUE*> holds
Intval z = - 1

proof end;

theorem :: BINARI_4:16

for z being Tuple of 1, BOOLEAN st z = <*FALSE*> holds
Intval z = 0

proof end;

theorem :: BINARI_4:17

for x being boolean object holds TRUE 'or' x = TRUE ;

theorem :: BINARI_4:18

for n being non zero Nat holds
( 0 <= (2 to_power (n -' 1)) - 1 & - (2 to_power (n -' 1)) <= 0 )

proof end;

theorem :: BINARI_4:19

for n being non zero Nat
for x, y being Tuple of n, BOOLEAN st x = 0* n & y = 0* n holds
x,y are_summable

proof end;

theorem Th20: :: BINARI_4:20

for n being non zero Nat
for i being Integer holds (i * n) mod n = 0 by NAT_D:71;

definition

let m, j be Nat;

func MajP (m,j) -> Nat means :Def1: :: BINARI_4:def 1
( 2 to_power it >= j & it >= m & ( for k being Nat st 2 to_power k >= j & k >= m holds
k >= it ) );

existence
ex b₁ being Nat st
( 2 to_power b₁ >= j & b₁ >= m & ( for k being Nat st 2 to_power k >= j & k >= m holds
k >= b₁ ) )

proof end;

uniqueness
for b₁, b₂ being Nat st 2 to_power b₁ >= j & b₁ >= m & ( for k being Nat st 2 to_power k >= j & k >= m holds
k >= b₁ ) & 2 to_power b₂ >= j & b₂ >= m & ( for k being Nat st 2 to_power k >= j & k >= m holds
k >= b₂ ) holds
b₁ = b₂

proof end;

end;

:: deftheorem Def1 defines MajP BINARI_4:def 1 :
for m, j, b₃ being Nat holds
( b₃ = MajP (m,j) iff ( 2 to_power b₃ >= j & b₃ >= m & ( for k being Nat st 2 to_power k >= j & k >= m holds
k >= b₃ ) ) );

theorem :: BINARI_4:21

for j, k, m being Nat st j >= k holds
MajP (m,j) >= MajP (m,k)

proof end;

theorem Th22: :: BINARI_4:22

for j, l, m being Nat st l >= m holds
MajP (l,j) >= MajP (m,j)

proof end;

theorem :: BINARI_4:23

for m being Nat st m >= 1 holds
MajP (m,1) = m

proof end;

theorem Th24: :: BINARI_4:24

for j, m being Nat st j <= 2 to_power m holds
MajP (m,j) = m

proof end;

theorem :: BINARI_4:25

for j, m being Nat st j > 2 to_power m holds
MajP (m,j) > m

proof end;

definition

let m be Nat;
let i be Integer;

func 2sComplement (m,i) -> Tuple of m, BOOLEAN equals :Def2: :: BINARI_4:def 2
m -BinarySequence |.((2 to_power (MajP (m,|.i.|))) + i).| if i < 0
otherwise m -BinarySequence |.i.|;

correctness
coherence
( ( i < 0 implies m -BinarySequence |.((2 to_power (MajP (m,|.i.|))) + i).| is Tuple of m, BOOLEAN ) & ( not i < 0 implies m -BinarySequence |.i.| is Tuple of m, BOOLEAN ) );
consistency
for b₁ being Tuple of m, BOOLEAN holds verum;
;

end;

:: deftheorem Def2 defines 2sComplement BINARI_4:def 2 :
for m being Nat
for i being Integer holds
( ( i < 0 implies 2sComplement (m,i) = m -BinarySequence |.((2 to_power (MajP (m,|.i.|))) + i).| ) & ( not i < 0 implies 2sComplement (m,i) = m -BinarySequence |.i.| ) );

theorem :: BINARI_4:26

for m being Nat holds 2sComplement (m,0) = 0* m

proof end;

theorem :: BINARI_4:27

for n being non zero Nat
for i being Integer st i <= (2 to_power (n -' 1)) - 1 & - (2 to_power (n -' 1)) <= i holds
Intval (2sComplement (n,i)) = i

proof end;

Lm1: for n being non zero Nat
for k, l being Nat st k mod n = l mod n & k > l holds
ex s being Integer st k = l + (s * n)

proof end;

Lm2: for n being non zero Nat
for k, l being Nat st k mod n = l mod n holds
ex s being Integer st k = l + (s * n)

proof end;

Lm3: for n being non zero Nat
for k, l, m being Nat st m < n & k mod (2 to_power n) = l mod (2 to_power n) holds
(k div (2 to_power m)) mod 2 = (l div (2 to_power m)) mod 2

proof end;

Lm4: for n being non zero Nat
for h, i being Integer st h mod (2 to_power n) = i mod (2 to_power n) holds
((2 to_power (MajP (n,|.h.|))) + h) mod (2 to_power n) = ((2 to_power (MajP (n,|.i.|))) + i) mod (2 to_power n)

proof end;

Lm5: for n being non zero Nat
for h, i being Integer st h >= 0 & i >= 0 & h mod (2 to_power n) = i mod (2 to_power n) holds
2sComplement (n,h) = 2sComplement (n,i)

proof end;

Lm6: for n being non zero Nat
for h, i being Integer st h < 0 & i < 0 & h mod (2 to_power n) = i mod (2 to_power n) holds
2sComplement (n,h) = 2sComplement (n,i)

proof end;

theorem :: BINARI_4:28

for n being non zero Nat
for h, i being Integer st ( ( h >= 0 & i >= 0 ) or ( h < 0 & i < 0 ) ) & h mod (2 to_power n) = i mod (2 to_power n) holds
2sComplement (n,h) = 2sComplement (n,i) by Lm5, Lm6;

theorem :: BINARI_4:29

for n being non zero Nat
for h, i being Integer st ( ( h >= 0 & i >= 0 ) or ( h < 0 & i < 0 ) ) & h,i are_congruent_mod 2 to_power n holds
2sComplement (n,h) = 2sComplement (n,i)

proof end;

theorem Th30: :: BINARI_4:30

for n being non zero Nat
for l, m being Nat st l mod (2 to_power n) = m mod (2 to_power n) holds
n -BinarySequence l = n -BinarySequence m

proof end;

theorem :: BINARI_4:31

for n being non zero Nat
for l, m being Nat st l,m are_congruent_mod 2 to_power n holds
n -BinarySequence l = n -BinarySequence m

proof end;

theorem Th32: :: BINARI_4:32

for n being non zero Nat
for i being Integer
for j being Nat st 1 <= j & j <= n holds
(2sComplement ((n + 1),i)) /. j = (2sComplement (n,i)) /. j

proof end;

theorem Th33: :: BINARI_4:33

for m being Nat
for i being Integer ex x being Element of BOOLEAN st 2sComplement ((m + 1),i) = (2sComplement (m,i)) ^ <*x*>

proof end;

theorem :: BINARI_4:34

for l, m being Nat ex x being Element of BOOLEAN st (m + 1) -BinarySequence l = (m -BinarySequence l) ^ <*x*>

proof end;

theorem Th35: :: BINARI_4:35

for h, i being Integer
for n being non zero Nat st - (2 to_power n) <= h + i & h < 0 & i < 0 & - (2 to_power (n -' 1)) <= h & - (2 to_power (n -' 1)) <= i holds
(carry ((2sComplement ((n + 1),h)),(2sComplement ((n + 1),i)))) /. (n + 1) = TRUE

proof end;

theorem :: BINARI_4:36

for h, i being Integer
for n being non zero Nat st h + i <= (2 to_power (n -' 1)) - 1 & h >= 0 & i >= 0 holds
Intval ((2sComplement (n,h)) + (2sComplement (n,i))) = h + i

proof end;

theorem :: BINARI_4:37

for h, i being Integer
for n being non zero Nat st - (2 to_power ((n + 1) -' 1)) <= h + i & h < 0 & i < 0 & - (2 to_power (n -' 1)) <= h & - (2 to_power (n -' 1)) <= i holds
Intval ((2sComplement ((n + 1),h)) + (2sComplement ((n + 1),i))) = h + i

proof end;

theorem :: BINARI_4:38

for h, i being Integer
for n being non zero Nat st - (2 to_power (n -' 1)) <= h & h <= (2 to_power (n -' 1)) - 1 & - (2 to_power (n -' 1)) <= i & i <= (2 to_power (n -' 1)) - 1 & - (2 to_power (n -' 1)) <= h + i & h + i <= (2 to_power (n -' 1)) - 1 & ( ( h >= 0 & i < 0 ) or ( h < 0 & i >= 0 ) ) holds
Intval ((2sComplement (n,h)) + (2sComplement (n,i))) = h + i

proof end;