theorem :: ZF_LANG:38

for F, H being ZF-formula st H is conjunctive holds
( ( F = the_left_argument_of H implies ex G being ZF-formula st F '&' G = H ) & ( ex G being ZF-formula st F '&' G = H implies F = the_left_argument_of H ) & ( F = the_right_argument_of H implies ex G being ZF-formula st G '&' F = H ) & ( ex G being ZF-formula st G '&' F = H implies F = the_right_argument_of H ) ) by Def31, Def32;