Copyright (c) 1996 Association of Mizar Users
environ vocabulary RELAT_2, LATTICE3, ORDERS_1, LATTICES, WAYBEL_0, ZF_LANG, BOOLE; notation STRUCT_0, LATTICE3, WAYBEL_0, WAYBEL_1, YELLOW_0, ORDERS_1; constructors WAYBEL_1, LATTICE3; clusters LATTICE3, WAYBEL_1; theorems LATTICE3, YELLOW_0, WAYBEL_1; begin :: Introduction theorem for L being reflexive antisymmetric with_suprema RelStr for a being Element of L holds a "\/" a = a proof let L be reflexive antisymmetric with_suprema RelStr, a be Element of L; A1: a <= a "\/" a by YELLOW_0:22; a <= a; then a "\/" a <= a by YELLOW_0:22; hence thesis by A1,YELLOW_0:def 3; end; theorem Th2: for L being reflexive antisymmetric with_infima RelStr for a being Element of L holds a "/\" a = a proof let L be reflexive antisymmetric with_infima RelStr, a be Element of L; A1: a "/\" a <= a by YELLOW_0:23; a <= a; then a <= a "/\" a by YELLOW_0:23; hence thesis by A1,YELLOW_0:def 3; end; theorem for L be transitive antisymmetric with_suprema RelStr for a,b,c being Element of L holds a"\/"b <= c implies a <= c proof let L be transitive antisymmetric with_suprema RelStr; let a,b,c be Element of L; assume A1: a"\/"b <= c; a <= a"\/"b by YELLOW_0:22; hence thesis by A1,YELLOW_0:def 2; end; theorem for L be transitive antisymmetric with_infima RelStr for a,b,c being Element of L holds c <= a"/\"b implies c <= a proof let L be transitive antisymmetric with_infima RelStr; let a,b,c be Element of L; assume A1: c <= a"/\"b; a"/\"b <= a by YELLOW_0:23; hence thesis by A1,YELLOW_0:def 2; end; theorem for L be antisymmetric transitive with_suprema with_infima RelStr for a,b,c being Element of L holds a"/\"b <= a"\/"c proof let L be antisymmetric transitive with_suprema with_infima RelStr; let a,b,c be Element of L; A1: a"/\"b <= a by YELLOW_0:23; a <= a"\/"c by YELLOW_0:22; hence thesis by A1,YELLOW_0:def 2; end; theorem Th6: for L be antisymmetric transitive with_infima RelStr for a,b,c be Element of L holds a <= b implies a"/\"c <= b"/\"c proof let L be antisymmetric transitive with_infima RelStr; let a,b,c be Element of L; assume A1: a <= b; a"/\"c <= a by YELLOW_0:23; then A2:a"/\"c <= b by A1,YELLOW_0:def 2; a"/\"c <= c by YELLOW_0:23; hence thesis by A2,YELLOW_0:23; end; theorem Th7: for L be antisymmetric transitive with_suprema RelStr for a,b,c be Element of L holds a <= b implies a"\/"c <= b"\/"c proof let L be non empty antisymmetric transitive with_suprema RelStr; let a,b,c be Element of L; assume A1: a <= b; b <= b "\/" c by YELLOW_0:22; then A2:a <= b "\/" c by A1,YELLOW_0:def 2; c <= b "\/" c by YELLOW_0:22; hence thesis by A2,YELLOW_0:22; end; theorem Th8: for L be sup-Semilattice for a,b be Element of L holds a <= b implies a "\/" b = b proof let L be sup-Semilattice; let a,b be Element of L; assume A1: a <= b; A2: b <= a "\/" b by YELLOW_0:22; b <= b; then a "\/" b <= b by A1,YELLOW_0:22; hence thesis by A2,YELLOW_0:def 3; end; theorem Th9: for L be sup-Semilattice for a,b,c being Element of L holds a <= c & b <= c implies a"\/"b <= c proof let L be sup-Semilattice; let a,b,c be Element of L; assume that A1: a <= c and A2: b <= c; c "\/" b = c by A2,Th8; hence thesis by A1,Th7; end; theorem Th10: for L be Semilattice for a,b be Element of L holds b <= a implies a"/\"b = b proof let L be Semilattice; let a,b be Element of L; assume A1: b <= a; A2: a"/\"b <= b by YELLOW_0:23; b "/\" b <= a "/\" b by A1,Th6; then b <= a "/\" b by Th2; hence thesis by A2,YELLOW_0:def 3; end; :: Difference in Relation Structure begin theorem Th11: for L being Boolean LATTICE, x,y being Element of L holds y is_a_complement_of x iff y = 'not' x proof let L be Boolean LATTICE, x,y be Element of L; A1: for x being Element of L holds 'not' 'not' x = x by WAYBEL_1:90; then 'not' x is_a_complement_of x by WAYBEL_1:89; then A2: x "\/" 'not' x = Top L & x "/\" 'not' x = Bottom L by WAYBEL_1:def 23 ; hereby assume y is_a_complement_of x; then A3: x "\/" y = Top L & x "/\" y = Bottom L by WAYBEL_1:def 23; A4: Bottom L <= y"/\"'not' x by YELLOW_0:44; Top L >= 'not' x by YELLOW_0:45; then A5: 'not' x = (x"\/"y)"/\"'not' x by A3,YELLOW_0:25 .= (x"/\"'not' x)"\/"(y"/\"'not' x) by WAYBEL_1:def 3 .= y"/\"'not' x by A2,A4,YELLOW_0:24; Top L >= y by YELLOW_0:45; then y = (x"\/"'not' x)"/\"y by A2,YELLOW_0:25 .= (x"/\"y)"\/"(y"/\"'not' x) by WAYBEL_1:def 3 .= y"/\"'not' x by A3,A4,YELLOW_0:24; hence y = 'not' x by A5; end; thus thesis by A1,WAYBEL_1:89; end; definition let L be non empty RelStr, a,b be Element of L; func a \ b -> Element of L equals :Def1: a "/\" 'not' b; correctness; end; definition let L be non empty RelStr, a, b be Element of L; func a \+\ b -> Element of L equals :Def2: (a \ b) "\/" (b \ a); correctness; end; Lm1: for L be antisymmetric with_infima with_suprema RelStr, a, b be Element of L holds a \+\ b = b \+\ a proof let L be antisymmetric with_infima with_suprema RelStr, a, b be Element of L; thus a \+\ b = (a \ b) "\/" (b \ a) by Def2 .= b \+\ a by Def2; end; definition let L be antisymmetric with_infima with_suprema RelStr, a, b be Element of L; redefine func a \+\ b; commutativity by Lm1; end; definition let L be non empty RelStr, a, b be Element of L; pred a meets b means :Def3: a "/\" b <> Bottom L; antonym a misses b; end; definition let L be with_infima antisymmetric RelStr, a, b be Element of L; redefine pred a meets b; symmetry proof let a, b be Element of L; a"/\"b <> Bottom L implies b"/\"a <> Bottom L; hence thesis by Def3; end; antonym a misses b; end; theorem for L be antisymmetric transitive with_infima with_suprema RelStr for a,b,c be Element of L holds a <= c implies a \ b <= c proof let L be antisymmetric transitive with_infima with_suprema RelStr; let a,b,c be Element of L; assume A1: a <= c; A2: a \ b = a "/\" 'not' b by Def1; a "/\" 'not' b <= a by YELLOW_0:23; hence thesis by A1,A2,YELLOW_0:def 2; end; theorem for L be antisymmetric transitive with_infima with_suprema RelStr for a,b,c be Element of L holds a <= b implies a \ c <= b \ c proof let L be antisymmetric transitive with_infima with_suprema RelStr; let a,b,c be Element of L; assume A1: a <= b; A2: a \ c = a "/\" 'not' c by Def1; b \ c = b "/\" 'not' c by Def1; hence thesis by A1,A2,Th6; end; theorem for L be antisymmetric transitive with_infima with_suprema RelStr for a,b be Element of L holds a \ b <= a proof let L be antisymmetric transitive with_infima with_suprema RelStr; let a,b be Element of L; a \ b = a "/\" 'not' b by Def1; hence thesis by YELLOW_0:23; end; theorem for L be antisymmetric transitive with_infima with_suprema RelStr for a,b be Element of L holds a \ b <= a \+\ b proof let L be antisymmetric transitive with_infima with_suprema RelStr, a,b be Element of L; a \ b <= (a \ b) "\/" (b \ a) by YELLOW_0:22; hence thesis by Def2; end; theorem for L be LATTICE for a,b,c be Element of L holds a \ b <= c & b \ a <= c implies a \+\ b <= c proof let L be LATTICE, a,b,c be Element of L; assume A1: a \ b <= c & b \ a <= c; a \+\ b = (a \ b) "\/" (b \ a) by Def2; hence thesis by A1,Th9; end; theorem for L be LATTICE for a be Element of L holds a meets a iff a <> Bottom L proof let L be LATTICE, a be Element of L; thus a meets a implies a <> Bottom L proof assume a meets a; then a "/\" a <> Bottom L by Def3; hence thesis by Th2; end; thus a <> Bottom L implies a meets a proof assume a <> Bottom L; then a "/\" a <> Bottom L by Th2; hence thesis by Def3; end; end; theorem for L be antisymmetric transitive with_infima with_suprema RelStr for a,b,c be Element of L holds a "/\" (b \ c) = (a "/\" b) \ c proof let L be antisymmetric transitive with_infima with_suprema RelStr; let a,b,c be Element of L; thus a "/\" (b \ c) = a "/\" (b "/\" 'not' c) by Def1 .= (a "/\" b) "/\" 'not' c by LATTICE3:16 .= (a "/\" b) \ c by Def1; end; theorem for L be antisymmetric transitive with_infima RelStr st L is distributive for a,b,c be Element of L holds (a "/\" b) "\/" (a "/\" c) = a implies a <= b "\/" c proof let L be antisymmetric transitive with_infima RelStr such that A1: L is distributive; let a,b,c be Element of L; assume (a "/\" b) "\/" (a "/\" c) = a; then (b "\/" c) "/\" a = a by A1,WAYBEL_1:def 3; hence thesis by YELLOW_0:23; end; theorem Th20: for L be LATTICE st L is distributive for a,b,c be Element of L holds a"\/"(b"/\"c) = (a"\/"b) "/\" (a"\/"c) proof let L be LATTICE such that A1: L is distributive; let a,b,c be Element of L; (a"\/"b) "/\" (a"\/"c) = ((a"\/"b) "/\" a) "\/"((a"\/"b) "/\" c) by A1,WAYBEL_1:def 3 .= a "\/" ((a"\/"b) "/\" c) by LATTICE3:18 .= a "\/" ((c"/\"a) "\/" (c"/\"b)) by A1,WAYBEL_1:def 3 .= (a "\/" (c"/\"a)) "\/" (c"/\"b) by LATTICE3:14 .= a "\/" (c"/\"b) by LATTICE3:17; hence thesis; end; theorem for L be LATTICE st L is distributive for a,b,c be Element of L holds (a "\/" b) \ c = (a \ c) "\/" (b \ c) proof let L be with_suprema with_infima reflexive transitive antisymmetric non empty RelStr such that A1: L is distributive; let a,b,c be Element of L; thus (a "\/" b) \ c = (a "\/" b) "/\" 'not' c by Def1 .= ('not' c "/\" a) "\/" ('not' c"/\" b) by A1,WAYBEL_1:def 3 .= (a \ c) "\/" (b "/\" 'not' c) by Def1 .= (a \ c) "\/" (b \ c) by Def1; end; :: Lower-bound in Relation Structure begin theorem Th22: for L be lower-bounded non empty antisymmetric RelStr for a be Element of L holds a <= Bottom L implies a = Bottom L proof let L be lower-bounded non empty antisymmetric RelStr; let a be Element of L; assume A1: a <= Bottom L; Bottom L <= a by YELLOW_0:44; hence thesis by A1,YELLOW_0:def 3; end; theorem for L be lower-bounded Semilattice for a,b,c be Element of L holds a <= b & a <= c & b"/\"c = Bottom L implies a = Bottom L proof let L be lower-bounded Semilattice; let a,b,c be Element of L; assume that A1: a <= b and A2: a <= c and A3: b"/\"c = Bottom L; a"/\"c <= b"/\"c by A1,Th6; then a <= b"/\"c by A2,Th10; hence thesis by A3,Th22; end; theorem for L be lower-bounded antisymmetric with_suprema RelStr for a,b be Element of L holds a"\/"b = Bottom L implies a = Bottom L & b = Bottom L proof let L be lower-bounded antisymmetric with_suprema RelStr; let a,b be Element of L; assume a"\/"b = Bottom L; then a <= Bottom L & b <= Bottom L by YELLOW_0:22; hence thesis by Th22; end; theorem for L be lower-bounded antisymmetric transitive with_infima RelStr for a,b,c be Element of L holds a <= b & b"/\"c = Bottom L implies a"/\"c = Bottom L proof let L be lower-bounded antisymmetric transitive with_infima RelStr; let a,b,c be Element of L; assume a <= b & b"/\"c = Bottom L; then A1: a"/\"c <= Bottom L by Th6; Bottom L <= a"/\"c by YELLOW_0:44; hence thesis by A1,YELLOW_0:def 3; end; theorem for L be lower-bounded Semilattice for a be Element of L holds Bottom L \ a = Bottom L proof let L be lower-bounded Semilattice; let a be Element of L; A1: Bottom L <= 'not' a by YELLOW_0:44; thus Bottom L \ a = Bottom L "/\" 'not' a by Def1 .= Bottom L by A1,Th10; end; theorem for L be lower-bounded antisymmetric transitive with_infima RelStr for a,b,c be Element of L holds a meets b & b <= c implies a meets c proof let L be lower-bounded antisymmetric transitive with_infima RelStr; let a,b,c be Element of L; assume that A1: a meets b; assume b <= c; then A2: a"/\"b <= a"/\"c by Th6; assume not (a meets c); then A3: not (a"/\"c <> Bottom L) by Def3; Bottom L <= a"/\"b by YELLOW_0:44; then a"/\"b = Bottom L by A2,A3,YELLOW_0:def 3; hence contradiction by A1,Def3; end; theorem Th28: for L be lower-bounded with_infima antisymmetric RelStr for a be Element of L holds a"/\"Bottom L = Bottom L proof let L be lower-bounded with_infima antisymmetric RelStr; let a be Element of L; A1: Bottom L <= a "/\" Bottom L by YELLOW_0:44; a"/\"Bottom L <= Bottom L by YELLOW_0:23; hence thesis by A1,YELLOW_0:def 3; end; theorem for L be lower-bounded antisymmetric transitive with_infima with_suprema RelStr for a,b,c be Element of L holds a meets b"/\"c implies a meets b proof let L be lower-bounded antisymmetric transitive with_infima with_suprema RelStr; let a,b,c be Element of L; assume A1: a meets b"/\"c; assume A2: not(a meets b); a"/\"(b"/\"c)= (a"/\"b)"/\"c by LATTICE3:16 .= Bottom L "/\"c by A2,Def3 .= Bottom L by Th28; hence contradiction by A1,Def3; end; theorem for L be lower-bounded antisymmetric transitive with_infima with_suprema RelStr for a,b,c be Element of L holds a meets b\c implies a meets b proof let L be lower-bounded antisymmetric transitive with_infima with_suprema RelStr; let a,b,c be Element of L; assume A1: a meets b\c; assume A2: not (a meets b); a"/\"(b\c) = a"/\"(b"/\"'not' c) by Def1 .= (a"/\"b)"/\"'not' c by LATTICE3:16 .= Bottom L "/\"'not' c by A2,Def3 .= Bottom L by Th28; hence contradiction by A1,Def3; end; theorem for L be lower-bounded antisymmetric transitive with_infima RelStr for a be Element of L holds a misses Bottom L proof let L be lower-bounded antisymmetric transitive with_infima RelStr; let a be Element of L; a "/\" Bottom L = Bottom L by Th28; hence thesis by Def3; end; theorem for L be lower-bounded antisymmetric transitive with_infima RelStr for a,b,c be Element of L holds a misses c & b <= c implies a misses b proof let L be lower-bounded antisymmetric transitive with_infima RelStr; let a,b,c be Element of L; assume that A1: a misses c and A2: b <= c; a"/\"c = Bottom L by A1,Def3; then A3: a"/\"b <= Bottom L by A2,Th6; Bottom L <= a"/\"b by YELLOW_0:44; then a"/\"b = Bottom L by A3,YELLOW_0:def 3; hence thesis by Def3; end; theorem for L be lower-bounded antisymmetric transitive with_infima RelStr for a,b,c be Element of L holds a misses b or a misses c implies a misses b"/\"c proof let L be lower-bounded antisymmetric transitive with_infima RelStr; let a,b,c be Element of L; assume A1: a misses b or a misses c; per cases by A1; suppose A2: a misses b; a"/\" (b"/\"c) = (a"/\"b)"/\"c by LATTICE3:16 .= Bottom L "/\" c by A2,Def3 .= Bottom L by Th28; hence a misses b"/\"c by Def3; suppose A3: a misses c; a"/\" (b"/\"c) = (a"/\"c)"/\"b by LATTICE3:16 .= Bottom L "/\" b by A3,Def3 .= Bottom L by Th28; hence a misses b"/\"c by Def3; thus thesis; end; theorem for L be lower-bounded LATTICE for a,b,c be Element of L holds a <= b & a <= c & b misses c implies a = Bottom L proof let L be lower-bounded LATTICE; let a,b,c be Element of L; assume that A1: a <= b and A2: a <= c and A3: b misses c; A4: b"/\"c = Bottom L by A3,Def3; A5: Bottom L <= a"/\"c by YELLOW_0:44; a"/\"c <= Bottom L by A1,A4,Th6; then a"/\"c = Bottom L by A5,YELLOW_0:def 3; hence thesis by A2,Th10; end; theorem for L be lower-bounded antisymmetric transitive with_infima RelStr for a,b,c be Element of L holds a misses b implies (a"/\"c) misses (b"/\"c) proof let L be lower-bounded antisymmetric transitive with_infima RelStr; let a,b,c be Element of L; assume A1: a misses b; (a"/\"c)"/\"(b"/\"c) = c"/\"(a"/\"(b"/\"c)) by LATTICE3:16 .= c"/\"(a"/\"b)"/\"c by LATTICE3:16 .= c"/\"Bottom L"/\"c by A1,Def3 .= Bottom L"/\"c by Th28 .=Bottom L by Th28; hence thesis by Def3; end; :: Boolean Lattice begin reserve L for Boolean (non empty RelStr); reserve a,b,c,d for Element of L; theorem (a"/\"b) "\/" (b"/\"c) "\/" (c"/\"a) = (a"\/"b) "/\" (b"\/"c) "/\" (c"\/"a) proof (a"/\"b) "\/" (b"/\"c) "\/" (c"/\"a) = ((a"\/"(b"/\"c)) "/\" (b"\/"(b"/\"c))) "\/" (c"/\"a) by WAYBEL_1:6 .= ((a"\/"(b"/\"c)) "/\" b) "\/" (c"/\"a) by LATTICE3:17 .= ((a"\/"(b"/\"c)) "\/" (c"/\"a)) "/\" (b "\/" (c"/\"a)) by WAYBEL_1:6 .= ((a"\/"(b"/\"c)) "\/" (c"/\"a)) "/\" ((b"\/"c) "/\" (b"\/" a)) by WAYBEL_1:6 .= ((b"/\"c)"\/"(a"\/"(c"/\"a))) "/\" ((b"\/"c) "/\" (b"\/" a)) by LATTICE3:14 .= ((b"/\"c)"\/"a) "/\" ((b"\/"c) "/\" (b"\/"a)) by LATTICE3:17 .= ((b"\/"a) "/\" (c"\/"a)) "/\" ((b"\/"c) "/\" (b"\/"a)) by WAYBEL_1:6 .= (b"\/"a) "/\" (((c"\/"a) "/\" (b"\/"a)) "/\" (b"\/"c)) by LATTICE3:16 .= (b"\/"a) "/\" ( (b"\/"a) "/\" ((c"\/"a) "/\" (b"\/"c))) by LATTICE3:16 .= ((b"\/"a) "/\" (b"\/"a)) "/\" ((c"\/"a) "/\" (b"\/"c)) by LATTICE3:16 .= (b"\/"a) "/\" ((c"\/"a) "/\" (b"\/"c)) by Th2 .= ((a"\/"b) "/\" (b"\/"c)) "/\" (c"\/"a) by LATTICE3:16; hence (a"/\"b)"\/" (b"/\"c) "\/" (c"/\"a) = (a"\/"b) "/\" (b"\/"c) "/\" (c "\/"a); end; theorem Th37: a"/\"'not' a = Bottom L & a"\/"'not' a = Top L proof 'not' a is_a_complement_of a by Th11; hence thesis by WAYBEL_1:def 23; end; theorem a \ b <= c implies a <= b"\/"c proof assume a \ b <= c; then a"/\"'not' b <= c by Def1; then A1: (a"/\"'not' b)"\/"b <= c"\/"b by Th7; A2: (a"/\"'not' b)"\/"b = (b"\/"a) "/\" (b"\/"'not' b) by Th20 .= (b"\/"a) "/\" Top L by Th37 .= a"\/"b by WAYBEL_1:5; a <= a"\/" b by YELLOW_0:22; hence thesis by A1,A2,YELLOW_0:def 2; end; theorem Th39: 'not' (a"\/"b) = 'not' a"/\" 'not' b & 'not' (a"/\"b) = 'not' a"\/" 'not' b proof thus 'not' (a"\/"b) = 'not' a"/\" 'not' b proof A1: (a"\/"b) "\/" ('not' a"/\" 'not' b) = a"\/"(b "\/" ('not' a"/\" 'not' b)) by LATTICE3:14 .= a"\/"((b"\/"'not' a)"/\"(b"\/"'not' b)) by Th20 .= a"\/"((b"\/"'not' a)"/\" Top L) by Th37 .= a"\/"(b"\/"'not' a) by WAYBEL_1:5 .= (a"\/"'not' a)"\/"b by LATTICE3:14 .= Top L"\/"b by Th37 .= Top L by WAYBEL_1:5; (a"\/"b) "/\" ('not' a"/\" 'not' b) = ((a"\/"b) "/\" 'not' a)"/\" 'not' b by LATTICE3:16 .= (('not' a"/\"a)"\/"('not' a"/\"b))"/\" 'not' b by WAYBEL_1:def 3 .= (Bottom L "\/"('not' a"/\"b))"/\" 'not' b by Th37 .= ('not' a"/\"b)"/\" 'not' b by WAYBEL_1:4 .= 'not' a"/\"(b"/\" 'not' b) by LATTICE3:16 .= 'not' a"/\" Bottom L by Th37 .= Bottom L by WAYBEL_1:4; then ('not' a"/\"'not' b) is_a_complement_of (a"\/" b) by A1,WAYBEL_1:def 23; hence thesis by Th11; end; thus 'not' (a"/\"b) = 'not' a"\/" 'not' b proof A2: (a"/\"b) "\/" ('not' a"\/" 'not' b) = ((a"/\"b) "\/"'not' a)"\/" 'not' b by LATTICE3:14 .= (('not' a"\/"a) "/\" ('not' a "\/"b) )"\/" 'not' b by Th20 .= (Top L "/\" ('not' a "\/"b) )"\/" 'not' b by Th37 .= ('not' a "\/"b)"\/" 'not' b by WAYBEL_1:5 .= 'not' a"\/"(b"\/" 'not' b) by LATTICE3:14 .= 'not' a"\/"Top L by Th37 .= Top L by WAYBEL_1:5; (a"/\"b) "/\" ('not' a"\/" 'not' b) = a"/\"(b"/\" ('not' a"\/" 'not' b)) by LATTICE3:16 .= a"/\"((b"/\"'not' a)"\/"(b"/\"'not' b)) by WAYBEL_1:def 3 .= a"/\"((b"/\"'not' a)"\/" Bottom L) by Th37 .= a"/\"(b"/\"'not' a) by WAYBEL_1:4 .= (a"/\"'not' a)"/\"b by LATTICE3:16 .= Bottom L"/\"b by Th37 .= Bottom L by WAYBEL_1:4; then ('not' a"\/" 'not' b) is_a_complement_of (a"/\" b) by A2,WAYBEL_1:def 23; hence thesis by Th11; end; end; theorem Th40: a <= b implies 'not' b <= 'not' a proof assume a <= b; then 'not' a = 'not' (b"/\"a) by Th10 .= 'not' b "\/" 'not' a by Th39; hence thesis by YELLOW_0:22; end; theorem a <= b implies c\b <= c\a proof assume a <= b; then 'not' b <= 'not' a by Th40; then c"/\"'not' b <= c"/\"'not' a by Th6; then c\b <= c"/\"'not' a by Def1; hence thesis by Def1; end; theorem a <= b & c <= d implies a\d <= b\c proof assume that A1: a <= b and A2: c <= d; 'not' d <= 'not' c by A2,Th40; then A3: a"/\"'not' d <= a"/\" 'not' c by Th6; a"/\"'not' c <= b"/\" 'not' c by A1,Th6; then a"/\"'not' d <= b"/\" 'not' c by A3,YELLOW_0:def 2; then a\d <= b"/\" 'not' c by Def1; hence thesis by Def1; end; theorem a <= b"\/"c implies a\b <= c & a\c <= b proof assume A1: a <= b"\/"c; A2: c"/\"'not' b <= c by YELLOW_0:23; (b"\/"c)"/\" 'not' b = ('not' b"/\"b) "\/" ('not' b"/\"c) by WAYBEL_1:def 3 .= Bottom L "\/" ('not' b"/\"c) by Th37 .= c"/\"'not' b by WAYBEL_1:4; then a"/\"'not' b <= c"/\"'not' b by A1,Th6; then a\b <= c"/\"'not' b by Def1; hence a\b <= c by A2,YELLOW_0:def 2; A3: 'not' c"/\"b <= b by YELLOW_0:23; (b"\/"c)"/\" 'not' c = ('not' c"/\"b) "\/" ('not' c"/\" c) by WAYBEL_1:def 3 .= ('not' c"/\"b)"\/" Bottom L by Th37 .= 'not' c"/\"b by WAYBEL_1:4; then a"/\"'not' c <= 'not' c"/\"b by A1,Th6; then a\c <= 'not' c"/\"b by Def1; hence a\c <= b by A3,YELLOW_0:def 2; end; theorem 'not' a <= 'not' (a"/\"b) & 'not' b <= 'not' (a"/\"b) proof 'not' a <= 'not' a"\/" 'not' b & 'not' b <= 'not' a"\/" 'not' b by YELLOW_0:22; hence thesis by Th39; end; theorem 'not' (a"\/"b) <= 'not' a & 'not' (a"\/"b) <= 'not' b proof 'not' a"/\"'not' b <= 'not' a & 'not' a"/\"'not' b <= 'not' b by YELLOW_0: 23 ; hence thesis by Th39; end; theorem a <= b\a implies a = Bottom L proof assume a <= b\a; then A1: a <= b"/\"'not' a by Def1; (b"/\"'not' a) "/\" a = b"/\"('not' a"/\"a) by LATTICE3:16 .= b"/\"Bottom L by Th37 .= Bottom L by WAYBEL_1:4; hence thesis by A1,Th10; end; theorem a <= b implies b = a "\/" (b\a) proof assume A1: a <= b; a "\/" (b\a) = a "\/" (b"/\"'not' a) by Def1 .= (a"\/"b) "/\" (a"\/"'not' a) by WAYBEL_1:6 .= b"/\"('not' a"\/"a) by A1,Th8 .= b"/\"Top L by Th37 .= b by WAYBEL_1:5; hence thesis; end; theorem a\b = Bottom L iff a <= b proof thus a\b = Bottom L implies a <= b proof assume a\b = Bottom L; then a"/\"'not' b = Bottom L by Def1; then (b"\/"a) "/\" (b "\/" 'not' b) <= b "\/"Bottom L by Th20; then (b"\/"a) "/\" (b "\/" 'not' b) <= b by WAYBEL_1:4; then (a"\/"b) "/\" Top L <= b by Th37; then A1: a"\/"b <= b by WAYBEL_1:5; a <= a "\/" b by YELLOW_0:22; hence thesis by A1,YELLOW_0:def 2; end; thus a <= b implies a\b = Bottom L proof assume a <= b; then a "/\" 'not' b <= b "/\"'not' b by Th6; then a "/\" 'not' b <= Bottom L by Th37; then A2: a\b <= Bottom L by Def1; Bottom L <= a\b by YELLOW_0:44; hence thesis by A2,YELLOW_0:def 3; end; end; theorem (a <= b"\/"c & a"/\"c = Bottom L) implies a <= b proof assume that A1: a <= b"\/"c and A2: a"/\"c = Bottom L; A3: a"/\"(b"\/"c) = a by A1,Th10; a"/\"(b"\/"c) = (a"/\"b)"\/" Bottom L by A2,WAYBEL_1:def 3; then a"/\"b = a by A3,WAYBEL_1:4; hence thesis by YELLOW_0:23; end; theorem a"\/"b = (a\b)"\/"b proof thus (a\b)"\/"b = (a"/\"'not' b)"\/"b by Def1 .= (b"\/"a)"/\"(b"\/"'not' b) by Th20 .= (b"\/"a)"/\" Top L by Th37 .= a"\/"b by WAYBEL_1:5; end; theorem a\(a"\/"b) = Bottom L proof thus a\(a"\/"b) = a"/\"'not' (a"\/"b) by Def1 .= a"/\"('not' a"/\"'not' b) by Th39 .= (a"/\"'not' a)"/\"'not' b by LATTICE3:16 .= Bottom L"/\"'not' b by Th37 .= Bottom L by WAYBEL_1:4; end; theorem a\a"/\"b = a\b proof thus a\a"/\"b = a"/\"'not' (a"/\"b) by Def1 .= a"/\"('not' a"\/"'not' b) by Th39 .= (a"/\"'not' a)"\/"(a"/\"'not' b) by WAYBEL_1:def 3 .= Bottom L "\/"(a"/\"'not' b) by Th37 .= a"/\"'not' b by WAYBEL_1:4 .= a\b by Def1; end; theorem (a\b)"/\"b = Bottom L proof thus (a\b)"/\"b = (a"/\"'not' b)"/\"b by Def1 .= a"/\"('not' b"/\"b) by LATTICE3:16 .= a"/\"Bottom L by Th37 .= Bottom L by WAYBEL_1:4; end; theorem a"\/"(b\a) = a"\/"b proof thus a"\/"(b\a) = a"\/"(b"/\"'not' a) by Def1 .= (a"\/"b)"/\"(a"\/"'not' a) by Th20 .= (a"\/"b)"/\"Top L by Th37 .= a"\/"b by WAYBEL_1:5; end; theorem (a"/\"b)"\/"(a\b) = a proof thus (a"/\"b)"\/"(a\b) = (a"/\"b)"\/"(a"/\"'not' b) by Def1 .= ((a"/\"b)"\/"a)"/\"((a"/\"b)"\/"'not' b) by Th20 .= a"/\"((a"/\"b)"\/"'not' b) by LATTICE3:17 .= a"/\"(('not' b"\/"a)"/\"('not' b"\/"b)) by Th20 .= a"/\"(('not' b"\/"a)"/\"Top L) by Th37 .= a"/\"('not' b"\/"a) by WAYBEL_1:5 .= a by LATTICE3:18; end; theorem a\(b\c)= (a\b)"\/"(a"/\"c) proof thus a\(b\c) = a"/\"'not' (b\c) by Def1 .= a"/\"'not' (b"/\"'not' c) by Def1 .= a"/\"('not' b"\/"'not' ('not' c)) by Th39 .= a"/\"('not' b"\/"c) by WAYBEL_1:90 .= (a"/\"'not' b)"\/"(a"/\"c) by WAYBEL_1:def 3 .= (a\b)"\/"(a"/\"c) by Def1; end; theorem a\(a\b) = a"/\"b proof thus a\(a\b) = a"/\"'not' (a\b) by Def1 .= a"/\"'not' (a"/\"'not' b) by Def1 .= a"/\"('not' a"\/"'not' 'not' b) by Th39 .= a"/\"('not' a"\/"b) by WAYBEL_1:90 .= (a"/\"'not' a)"\/"(a"/\"b) by WAYBEL_1:def 3 .= Bottom L"\/"(a"/\"b) by Th37 .= a"/\"b by WAYBEL_1:4; end; theorem (a"\/"b)\b = a\b proof thus (a"\/"b)\b = (a"\/"b)"/\"'not' b by Def1 .= (a"/\"'not' b)"\/"(b"/\"'not' b) by WAYBEL_1:def 3 .= (a"/\"'not' b)"\/"Bottom L by Th37 .= a"/\"'not' b by WAYBEL_1:4 .= a\b by Def1; end; theorem a"/\"b = Bottom L iff a\b = a proof thus a"/\"b = Bottom L implies a\b = a proof assume a"/\"b = Bottom L; then a <= 'not' b by WAYBEL_1:85; then a"/\"a <= a"/\"'not' b by Th6; then a <= a"/\"'not' b by Th2; then A1: a <= a\b by Def1; a\b = a"/\"'not' b by Def1; then a\b <= a by YELLOW_0:23; hence thesis by A1,YELLOW_0:def 3; end; thus a\b = a implies a"/\"b = Bottom L proof assume a\b = a; then a"/\"'not' b = a by Def1; then 'not' a"\/"'not' 'not' b = 'not' a by Th39; then a"/\"('not' a"\/"b) <= a"/\"'not' a by WAYBEL_1:90; then (a"/\"'not' a)"\/"(a"/\"b) <= a"/\"'not' a by WAYBEL_1:def 3; then Bottom L"\/"(a"/\"b) <= a"/\"'not' a by Th37; then Bottom L"\/"(a"/\"b) <= Bottom L by Th37; then A2: a"/\"b <= Bottom L by WAYBEL_1:4; Bottom L <= a"/\"b by YELLOW_0:44; hence thesis by A2,YELLOW_0:def 3; end; end; theorem a\(b"\/"c) = (a\b)"/\"(a\c) proof thus a\(b"\/"c) = a"/\"'not' (b"\/"c) by Def1 .= a"/\"('not' b"/\"'not' c) by Th39 .= (a"/\"a)"/\"('not' b"/\"'not' c) by Th2 .= ((a"/\"a)"/\"'not' b)"/\"'not' c by LATTICE3:16 .= (a"/\"(a"/\"'not' b))"/\"'not' c by LATTICE3:16 .= (a"/\"'not' b)"/\" (a"/\"'not' c) by LATTICE3:16 .= (a\b)"/\" (a"/\"'not' c) by Def1 .= (a\b)"/\" (a\c) by Def1; end; theorem a\(b"/\"c) = (a\b)"\/"(a\c) proof thus a\(b"/\"c) = a"/\"'not' (b"/\"c) by Def1 .= a"/\"('not' b"\/"'not' c) by Th39 .= (a"/\"'not' b)"\/"(a"/\"'not' c) by WAYBEL_1:def 3 .= (a\b)"\/"(a"/\"'not' c) by Def1 .= (a\b)"\/"(a\c) by Def1; end; theorem a"/\"(b\c) = a"/\"b \ a"/\"c proof thus a"/\"b \ a"/\"c = (a"/\"b) "/\"'not' (a"/\"c) by Def1 .= (a"/\"b) "/\"('not' a"\/"'not' c) by Th39 .= ((a"/\"b)"/\"'not' a)"\/"((a"/\"b)"/\" 'not' c) by WAYBEL_1:def 3 .= ((a"/\"'not' a)"/\"b)"\/"((a"/\"b)"/\" 'not' c) by LATTICE3:16 .= (Bottom L"/\"b)"\/"((a"/\"b)"/\"'not' c) by Th37 .= Bottom L"\/"((a"/\"b)"/\"'not' c) by WAYBEL_1:4 .= (a"/\"b)"/\"'not' c by WAYBEL_1:4 .= a"/\"(b"/\"'not' c) by LATTICE3:16 .= a"/\"(b\c) by Def1; end; theorem (a"\/"b)\(a"/\"b) = (a\b)"\/"(b\a) proof thus (a"\/"b)\(a"/\"b) = (a"\/"b)"/\"'not' (a"/\"b) by Def1 .= (a"\/"b)"/\"('not' a"\/"'not' b) by Th39 .= ((a"\/"b)"/\"'not' a)"\/"((a"\/"b)"/\" 'not' b) by WAYBEL_1:def 3 .= ((a"/\"'not' a)"\/"(b"/\"'not' a))"\/"((a"\/"b)"/\" 'not' b) by WAYBEL_1:def 3 .= (Bottom L"\/"(b"/\"'not' a))"\/"((a"\/"b)"/\"'not' b) by Th37 .= (b"/\"'not' a)"\/"((a"\/"b)"/\"'not' b) by WAYBEL_1:4 .= (b\a)"\/"((a"\/"b)"/\"'not' b) by Def1 .= (b\a)"\/"((a"/\"'not' b)"\/"(b"/\" 'not' b)) by WAYBEL_1:def 3 .= (b\a)"\/"((a"/\"'not' b)"\/"Bottom L) by Th37 .= (b\a)"\/"(a"/\"'not' b) by WAYBEL_1:4 .= (a\b)"\/"(b\a) by Def1; end; theorem (a\b)\c = a\(b"\/"c) proof thus (a\b)\c = (a"/\"'not' b)\c by Def1 .= (a"/\"'not' b)"/\"'not' c by Def1 .= a"/\"('not' b"/\"'not' c) by LATTICE3:16 .= a"/\"'not' (b"\/"c) by Th39 .= a\(b"\/"c) by Def1; end; theorem Th65: 'not' (Bottom L) = Top L proof A1: Bottom L "/\" Top L = Bottom L by WAYBEL_1:4; Bottom L "\/" Top L = Top L by WAYBEL_1:5; then Top L is_a_complement_of Bottom L by A1,WAYBEL_1:def 23; hence thesis by Th11; end; theorem 'not' (Top L) = Bottom L proof A1: Bottom L "/\" Top L = Bottom L by WAYBEL_1:4; Bottom L "\/" Top L = Top L by WAYBEL_1:5; then Bottom L is_a_complement_of Top L by A1,WAYBEL_1:def 23; hence thesis by Th11; end; theorem a\a = Bottom L proof thus a\a = a"/\"'not' a by Def1 .= Bottom L by Th37; end; theorem a \ Bottom L = a proof thus a \ Bottom L = a"/\"'not' (Bottom L) by Def1 .= a"/\"Top L by Th65 .= a by WAYBEL_1:5; end; theorem 'not' (a\b) = 'not' a"\/"b proof thus 'not' (a\b) = 'not' (a"/\"'not' b) by Def1 .= 'not' a"\/"'not' 'not' b by Th39 .= 'not' a"\/"b by WAYBEL_1:90; end; theorem a"/\"b misses a\b proof (a"/\"b)"/\"(a\b) = (a"/\"b)"/\"(a"/\"'not' b) by Def1 .= ((a"/\"b)"/\"'not' b)"/\"a by LATTICE3:16 .= (a"/\"(b"/\"'not' b))"/\"a by LATTICE3:16 .= (a"/\"Bottom L)"/\"a by Th37 .= Bottom L"/\"a by WAYBEL_1:4 .= Bottom L by WAYBEL_1:4; hence thesis by Def3; end; theorem (a\b) misses b proof (a\b)"/\"b = (a"/\"'not' b)"/\"b by Def1 .= a"/\"('not' b"/\"b) by LATTICE3:16 .= a"/\"Bottom L by Th37 .= Bottom L by WAYBEL_1:4; hence thesis by Def3; end; theorem a misses b implies (a"\/"b)\b = a proof assume a misses b; then a"/\"b = Bottom L by Def3; then (a"\/"'not' b)"/\"(b"\/"'not' b) <= Bottom L "\/"'not' b by Th20; then (a"\/"'not' b)"/\"(b"\/"'not' b) <= 'not' b by WAYBEL_1:4; then (a"\/"'not' b)"/\"Top L <= 'not' b by Th37; then A1: a"\/"'not' b <= 'not' b by WAYBEL_1:5; 'not' b <= a"\/"'not' b by YELLOW_0:22; then a"\/"'not' b = 'not' b by A1,YELLOW_0:def 3; then A2: a <= 'not' b by YELLOW_0:22; (a"\/"b)\b = (a"\/"b)"/\"'not' b by Def1 .= (a"/\"'not' b)"\/"(b"/\"'not' b) by WAYBEL_1:def 3 .= (a"/\"'not' b)"\/"Bottom L by Th37 .= a"/\"'not' b by WAYBEL_1:4 .= a by A2,Th10; hence thesis; end;