$P_1 \vee P_2 $ , $Q_1 \vee Q_2 $ are semi-decidable predicates and $P_2 = \overline{Q_2}$. What can be said about $P_1 \vee Q_1 $?
14849
Decidability of a predicate.
158295
First Order Logic clauses decidability
124295
Divison and remainder in Prolog
113411
If $E$ is generated by $E_1$ and $E_2$, then $[E:F]\leq [E_1:F][E_2:F]$?
69748
Semi-Ambiguous Combinatorics Problem
124742
P(A|C)=P(A|B)*P(B|C)?
1712
$ d_1,d_2\mid n\iff {\rm lcm}(d_1,d_2)\mid n\ $ [LCM Universal Property]
104771
Dedekind's cut and axioms
31299
Using the Fitch system, how do I prove $((p \implies q) \implies p)\implies p$?
61471
Decidability of the Riemann Hypothesis vs. the Goldbach Conjecture
47161
Quick logic question about $P\leftrightarrow Q$, terminology
69740
Is the following statement true ? If $L$ is a decidable language and $L' \subseteq \; L$, then $L'$ is also decidable ? Prove your answer is correct
29031
How does "If $P$ then $Q$" have the same meaning as "$Q$ only if $P$ "?
834
If $p$ is a prime and $p \mid ab$, then $p \mid a$ or $p \mid b$.
113342
Confusion of the decidability of $(N,s)$
103732
Proving that for $n \equiv 0 \pmod{2}$, we get ${n \choose 0} < {n \choose 1} <\ldots< {n \choose n/2-1}<{n\choose n/2}$ etc.
46430
A simple decision problem whose decidability is not known