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Theorem dcor 935

Description: A disjunction of two decidable propositions is decidable. (Contributed by Jim Kingdon, 21-Apr-2018.)

**Assertion**
Ref	Expression
dcor	DECID DECID DECID $\/$

**Proof of Theorem dcor**
Step	Hyp	Ref	Expression
1		df-dc 835	. 2 DECID $\/$
2		orc 712	. . . . . 6 $\/$
3	2	orcd 733	. . . . 5 $\/$ $\/$ $\/$
4		df-dc 835	. . . . 5 DECID $\/$ $\/$ $\/$ $\/$
5	3, 4	sylibr 134	. . . 4 DECID $\/$
6	5	a1d 22	. . 3 DECID DECID $\/$
7		df-dc 835	. . . . 5 DECID $\/$
8		olc 711	. . . . . . . . 9 $\/$
9	8	adantl 277	. . . . . . . 8 $/\$ $\/$
10	9	orcd 733	. . . . . . 7 $/\$ $\/$ $\/$ $\/$
11	10, 4	sylibr 134	. . . . . 6 $/\$ DECID $\/$
12		ioran 752	. . . . . . . . 9 $\/$ $/\$
13	12	biimpri 133	. . . . . . . 8 $/\$ $\/$
14	13	olcd 734	. . . . . . 7 $/\$ $\/$ $\/$ $\/$
15	14, 4	sylibr 134	. . . . . 6 $/\$ DECID $\/$
16	11, 15	jaodan 797	. . . . 5 $/\$ $\/$ DECID $\/$
17	7, 16	sylan2b 287	. . . 4 $/\$ DECID DECID $\/$
18	17	ex 115	. . 3 DECID DECID $\/$
19	6, 18	jaoi 716	. 2 $\/$ DECID DECID $\/$
20	1, 19	sylbi 121	1 DECID DECID DECID $\/$

Colors of variables: wff set class

Syntax hints:

wn 3

wi 4 $/\$ wa 104 $\/$ wo 708 DECID wdc 834

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-in1 614 ax-in2 615 ax-io 709

This theorem depends on definitions: df-bi 117 df-dc 835

This theorem is referenced by: pm4.55dc 938 orandc 939 pm3.12dc 958 pm3.13dc 959 dn1dc 960 eueq3dc 2912 distrlem4prl 7583 distrlem4pru 7584 exfzdc 10240 lcmmndc 12062 isprm3 12118 lgsval 14408 lgsfvalg 14409 lgsfcl2 14410 lgsval2lem 14414 lgsdir2 14437 lgsne0 14442 lgsdirnn0 14451 lgsdinn0 14452