set G = MSSCat A;
thus MSSCat A is transitive :: thesis: ( MSSCat A is associative & MSSCat A is with_units )
proof
let o1, o2, o3 be object of (MSSCat A); :: according to ALTCAT_1:def 4 :: thesis: ( <^o1,o2^> = {} or <^o2,o3^> = {} or not <^o1,o3^> = {} )
reconsider o1' = o1, o2' = o2, o3' = o3 as Element of MSS_set A by Def1;
assume ( <^o1,o2^> <> {} & <^o2,o3^> <> {} ) ; :: thesis: not <^o1,o3^> = {}
then A1: ( MSS_morph o1',o2' <> {} & MSS_morph o2',o3' <> {} ) by Def1;
consider t being Element of MSS_morph o1',o2';
consider s being Element of MSS_morph o2',o3';
consider f, g being Function such that
A2: ( t = [f,g] & f,g form_morphism_between o1',o2' ) by A1, MSALIMIT:def 10;
consider u, w being Function such that
A3: ( s = [u,w] & u,w form_morphism_between o2',o3' ) by A1, MSALIMIT:def 10;
u * f,w * g form_morphism_between o1',o3' by A2, A3, PUA2MSS1:30;
then [(u * f),(w * g)] in MSS_morph o1',o3' by MSALIMIT:def 10;
hence not <^o1,o3^> = {} by Def1; :: thesis: verum
end;
set M = MSSCat A;
set G = the Arrows of (MSSCat A);
set C = the Comp of (MSSCat A);
thus the Comp of (MSSCat A) is associative :: according to ALTCAT_1:def 17 :: thesis: MSSCat A is with_units
proof
let i, j, k, l be Element of (MSSCat A); :: according to ALTCAT_1:def 7 :: thesis: for b1, b2, b3 being set holds
( not b1 in the Arrows of (MSSCat A) . i,j or not b2 in the Arrows of (MSSCat A) . j,k or not b3 in the Arrows of (MSSCat A) . k,l or (the Comp of (MSSCat A) . i,k,l) . b3,((the Comp of (MSSCat A) . i,j,k) . b2,b1) = (the Comp of (MSSCat A) . i,j,l) . ((the Comp of (MSSCat A) . j,k,l) . b3,b2),b1 )

reconsider i' = i, j' = j, k' = k, l' = l as Element of MSS_set A by Def1;
reconsider I = i, J = j, K = k, L = l as object of (MSSCat A) ;
( I in the carrier of (MSSCat A) & J in the carrier of (MSSCat A) & K in the carrier of (MSSCat A) & L in the carrier of (MSSCat A) ) ;
then A4: ( I in MSS_set A & J in MSS_set A & K in MSS_set A & L in MSS_set A ) by Def1;
let f, g, h be set ; :: thesis: ( not f in the Arrows of (MSSCat A) . i,j or not g in the Arrows of (MSSCat A) . j,k or not h in the Arrows of (MSSCat A) . k,l or (the Comp of (MSSCat A) . i,k,l) . h,((the Comp of (MSSCat A) . i,j,k) . g,f) = (the Comp of (MSSCat A) . i,j,l) . ((the Comp of (MSSCat A) . j,k,l) . h,g),f )
assume A5: ( f in the Arrows of (MSSCat A) . i,j & g in the Arrows of (MSSCat A) . j,k & h in the Arrows of (MSSCat A) . k,l ) ; :: thesis: (the Comp of (MSSCat A) . i,k,l) . h,((the Comp of (MSSCat A) . i,j,k) . g,f) = (the Comp of (MSSCat A) . i,j,l) . ((the Comp of (MSSCat A) . j,k,l) . h,g),f
then A6: ( f in MSS_morph i',j' & g in MSS_morph j',k' & h in MSS_morph k',l' ) by Def1;
then consider f1, f2 being Function such that
A7: ( f = [f1,f2] & f1,f2 form_morphism_between i',j' ) by MSALIMIT:def 10;
consider g1, g2 being Function such that
A8: ( g = [g1,g2] & g1,g2 form_morphism_between j',k' ) by A6, MSALIMIT:def 10;
consider h1, h2 being Function such that
A9: ( h = [h1,h2] & h1,h2 form_morphism_between k',l' ) by A6, MSALIMIT:def 10;
A10: (the Comp of (MSSCat A) . i,j,k) . g,f = [(g1 * f1),(g2 * f2)] by A5, A7, A8, Def1;
g1 * f1,g2 * f2 form_morphism_between i',k' by A7, A8, PUA2MSS1:30;
then [(g1 * f1),(g2 * f2)] in MSS_morph i',k' by MSALIMIT:def 10;
then [(g1 * f1),(g2 * f2)] in the Arrows of (MSSCat A) . i,k by Def1;
then A11: (the Comp of (MSSCat A) . i,k,l) . h,[(g1 * f1),(g2 * f2)] = [(h1 * (g1 * f1)),(h2 * (g2 * f2))] by A4, A5, A9, Def1;
A12: (the Comp of (MSSCat A) . j,k,l) . h,g = [(h1 * g1),(h2 * g2)] by A5, A8, A9, Def1;
h1 * g1,h2 * g2 form_morphism_between j',l' by A8, A9, PUA2MSS1:30;
then [(h1 * g1),(h2 * g2)] in MSS_morph j',l' by MSALIMIT:def 10;
then A13: [(h1 * g1),(h2 * g2)] in the Arrows of (MSSCat A) . j,l by Def1;
( (h1 * g1) * f1 = h1 * (g1 * f1) & (h2 * g2) * f2 = h2 * (g2 * f2) ) by RELAT_1:55;
hence (the Comp of (MSSCat A) . i,k,l) . h,((the Comp of (MSSCat A) . i,j,k) . g,f) = (the Comp of (MSSCat A) . i,j,l) . ((the Comp of (MSSCat A) . j,k,l) . h,g),f by A4, A5, A7, A10, A11, A12, A13, Def1; :: thesis: verum
end;
thus the Comp of (MSSCat A) is with_left_units :: according to ALTCAT_1:def 18 :: thesis: the Comp of (MSSCat A) is with_right_units
proof
let j be Element of (MSSCat A); :: according to ALTCAT_1:def 9 :: thesis: ex b1 being set st
( b1 in the Arrows of (MSSCat A) . j,j & ( for b2 being Element of the carrier of (MSSCat A)
for b3 being set holds
( not b3 in the Arrows of (MSSCat A) . b2,j or (the Comp of (MSSCat A) . b2,j,j) . b1,b3 = b3 ) ) )

reconsider j' = j as Element of MSS_set A by Def1;
set e1 = id the carrier of j';
set e2 = id the carrier' of j';
A14: id the carrier of j', id the carrier' of j' form_morphism_between j',j' by PUA2MSS1:29;
take e = [(id the carrier of j'),(id the carrier' of j')]; :: thesis: ( e in the Arrows of (MSSCat A) . j,j & ( for b1 being Element of the carrier of (MSSCat A)
for b2 being set holds
( not b2 in the Arrows of (MSSCat A) . b1,j or (the Comp of (MSSCat A) . b1,j,j) . e,b2 = b2 ) ) )

the Arrows of (MSSCat A) . j,j = MSS_morph j',j' by Def1;
hence A15: e in the Arrows of (MSSCat A) . j,j by A14, MSALIMIT:def 10; :: thesis: for b1 being Element of the carrier of (MSSCat A)
for b2 being set holds
( not b2 in the Arrows of (MSSCat A) . b1,j or (the Comp of (MSSCat A) . b1,j,j) . e,b2 = b2 )

let i be Element of (MSSCat A); :: thesis: for b1 being set holds
( not b1 in the Arrows of (MSSCat A) . i,j or (the Comp of (MSSCat A) . i,j,j) . e,b1 = b1 )

let f be set ; :: thesis: ( not f in the Arrows of (MSSCat A) . i,j or (the Comp of (MSSCat A) . i,j,j) . e,f = f )
reconsider i' = i as Element of MSS_set A by Def1;
assume A16: f in the Arrows of (MSSCat A) . i,j ; :: thesis: (the Comp of (MSSCat A) . i,j,j) . e,f = f
then f in MSS_morph i',j' by Def1;
then consider f1, f2 being Function such that
A17: ( f = [f1,f2] & f1,f2 form_morphism_between i',j' ) by MSALIMIT:def 10;
reconsider I = i, J = j as object of (MSSCat A) ;
A18: (the Comp of (MSSCat A) . I,J,J) . [(id the carrier of j'),(id the carrier' of j')],[f1,f2] = [((id the carrier of j') * f1),((id the carrier' of j') * f2)] by A15, A16, A17, Def1;
A19: ( rng f1 c= the carrier of j' & rng f2 c= the carrier' of j' ) by A17, PUA2MSS1:def 13;
then (id the carrier of j') * f1 = f1 by RELAT_1:79;
hence (the Comp of (MSSCat A) . i,j,j) . e,f = f by A17, A18, A19, RELAT_1:79; :: thesis: verum
end;
thus the Comp of (MSSCat A) is with_right_units :: thesis: verum
proof
let i be Element of (MSSCat A); :: according to ALTCAT_1:def 8 :: thesis: ex b1 being set st
( b1 in the Arrows of (MSSCat A) . i,i & ( for b2 being Element of the carrier of (MSSCat A)
for b3 being set holds
( not b3 in the Arrows of (MSSCat A) . i,b2 or (the Comp of (MSSCat A) . i,i,b2) . b3,b1 = b3 ) ) )

reconsider i' = i as Element of MSS_set A by Def1;
set e1 = id the carrier of i';
set e2 = id the carrier' of i';
A20: id the carrier of i', id the carrier' of i' form_morphism_between i',i' by PUA2MSS1:29;
take e = [(id the carrier of i'),(id the carrier' of i')]; :: thesis: ( e in the Arrows of (MSSCat A) . i,i & ( for b1 being Element of the carrier of (MSSCat A)
for b2 being set holds
( not b2 in the Arrows of (MSSCat A) . i,b1 or (the Comp of (MSSCat A) . i,i,b1) . b2,e = b2 ) ) )

the Arrows of (MSSCat A) . i,i = MSS_morph i',i' by Def1;
hence A21: e in the Arrows of (MSSCat A) . i,i by A20, MSALIMIT:def 10; :: thesis: for b1 being Element of the carrier of (MSSCat A)
for b2 being set holds
( not b2 in the Arrows of (MSSCat A) . i,b1 or (the Comp of (MSSCat A) . i,i,b1) . b2,e = b2 )

let j be Element of (MSSCat A); :: thesis: for b1 being set holds
( not b1 in the Arrows of (MSSCat A) . i,j or (the Comp of (MSSCat A) . i,i,j) . b1,e = b1 )

let f be set ; :: thesis: ( not f in the Arrows of (MSSCat A) . i,j or (the Comp of (MSSCat A) . i,i,j) . f,e = f )
reconsider j' = j as Element of MSS_set A by Def1;
assume A22: f in the Arrows of (MSSCat A) . i,j ; :: thesis: (the Comp of (MSSCat A) . i,i,j) . f,e = f
then f in MSS_morph i',j' by Def1;
then consider f1, f2 being Function such that
A23: ( f = [f1,f2] & f1,f2 form_morphism_between i',j' ) by MSALIMIT:def 10;
reconsider I = i, J = j as object of (MSSCat A) ;
A24: (the Comp of (MSSCat A) . I,I,J) . [f1,f2],[(id the carrier of i'),(id the carrier' of i')] = [(f1 * (id the carrier of i')),(f2 * (id the carrier' of i'))] by A21, A22, A23, Def1;
A25: ( dom f1 = the carrier of i' & dom f2 = the carrier' of i' ) by A23, PUA2MSS1:def 13;
then f1 * (id the carrier of i') = f1 by RELAT_1:78;
hence (the Comp of (MSSCat A) . i,i,j) . f,e = f by A23, A24, A25, RELAT_1:78; :: thesis: verum
end;