factor_1 Theory

Introduces the theory of divisibility in cancellation monoids, and builds up to theorem characterizing when unique factorizations exist and are unique.

The theory here is developed constructively. Some theorems computable content is `useful': e.g. mfact_exists. An instantiation of this theorem is posint_is_ufm, which has as extract, a theorem to compute prime factorisations. Other theorems have computational content which is for most purposes uninteresting. e.g. look at theorem unique_mfact.

The theorem unique_mfact nicely demonstrates rewriting with equivalence relations of differing strengths: e.g. permr and permr_upto.


Summary of Definitions


Typed Definitions

mdivides *2
rev_mdivides *1
munit *1
mpdivides *1
massoc *1
mprime *1
mprime_ty *1
mreducible *1
matomic *1
matom_ty *1
permr_massoc *1
uni_sat_upto *1
exists_uni_upto *1
permr_massoc_rel *1
is_ufm *1
posint_mul_mon *11

Main Theorems

mdivides_id *3
mdivides_refl *3
mdivides_trans *6
mdivides_preorder *4
mdivides_cancel *6
munit_char *4
munit_of_op *9
non_munit_diff_imp_mpdivides *10
mdivides_weakening *2
massoc_equiv_rel *4
massoc_weakening *6
massoc_inversion *5
massoc_transitivity *5
grp_op_ap2_functionality_wrt_massoc *5
grp_op_ap2_functionality_wrt_mdivides *4
massoc_functionality_wrt_massoc *3
massoc_cancel *3
massoc_imp_unit_diff *14
sq_stable__mprime *5
mproper_div_cond *9
mreducible_elim *16
mdivisor_of_atom_is_assoc *11
mcomp_imp_not_unit *15
mprime_imp_matomic *20
mprime_divs_list_el *17
permr_massoc_weakening *4
permr_massoc_functionality *5
cons_functionality_wrt_permr_massoc *4
mfact_exists *18
mfact_exists_a *7
unique_mfact *34
exists_uni_upto_char *5
ufm_char *12
posint_cancel *7
posint_munit_elim *5
posint_well_fnd *11
posint_reduc_dec *12
posint_unit_dec *2
posint_div_dec *1
posint_atom_imp_prime *1
posint_fact_exists *30
posint_is_ufm *6

Listing


Last modified February 24th, 1995

Paul Jackson / jackson@cs.cornell.edu