set A = (carr H1) /\ (carr H2);
1_ G in H2 by Th46;
then A1: 1_ G in the carrier of H2 ;

A2: now :: thesis:

let g1, g2 be Element of G; :: thesis:
assume A3: ( g1 in (carr H1) /\ (carr H2) & g2 in (carr H1) /\ (carr H2) ) ; :: thesis:
then ( g1 in carr H2 & g2 in carr H2 ) by XBOOLE_0:def 4;
then A4: g1 * g2 in carr H2 by Th74;
( g1 in carr H1 & g2 in carr H1 ) by A3, XBOOLE_0:def 4;
then g1 * g2 in carr H1 by Th74;
hence g1 * g2 in (carr H1) /\ (carr H2) by A4, XBOOLE_0:def 4; :: thesis:

end;

A5: now :: thesis:

let g be Element of G; :: thesis:
assume A6: g in (carr H1) /\ (carr H2) ; :: thesis:
then g in carr H2 by XBOOLE_0:def 4;
then A7: g " in carr H2 by Th75;
g in carr H1 by A6, XBOOLE_0:def 4;
then g " in carr H1 by Th75;
hence g " in (carr H1) /\ (carr H2) by A7, XBOOLE_0:def 4; :: thesis:

end;

1_ G in H1 by Th46;
then 1_ G in the carrier of H1 ;
then (carr H1) /\ (carr H2) <> {} by A1, XBOOLE_0:def 4;
hence ex b₁ being strict Subgroup of G st the carrier of b₁ = (carr H1) /\ (carr H2) by A2, A5, Th52; :: thesis: