Def  b | a == c:. a = bc

is mentioned by

Thm*  x:{2...}, y:. prime(y)  x | y  x = y	[prime_nat_divby_self_only]
Thm*  b:. prime(b)  b | 1	[no_prime_divs_one_b]
Thm*  b:. b | 1  prime(b)	[no_prime_divs_one]
Thm*  b:. b | 1  prime(b)	[no_nat_prime_divs_one]
Thm*  x:{2...}. p:{2...}. px & prime(p) & p | x	[prime_or_smaller_prime_factor]
Thm*  x:. prime(x)  (i:{2..x}. i | x)	[natprime_nondivs]
Thm*  x:. prime(x)  2x & (i:{2..x}. i | x)	[prime_nat]
Thm*  b:. b | 1  b = 1	[only_one_nat_divs_one]
Thm*  a,b:. a | b  (c:. b = ac)	[divides_def_on_nat]

In prior sections: num thy 1

Try larger context: DiscrMathExt IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html