" The hardest logic puzzle ever " presented by George Boolos became a target for philosophers and logicians who tried to modify it and make it even tougher. I propose further modification of the original puzzle where part of the available information is eliminated but the solution is still possible. The solution also gives interesting ideas on logic behind discovery of unknown language.

In this paper, we give an overview of some recent work on applying tools from category theory in finite model theory, descriptive complexity, constraint satisfaction, and combinatorics. The motivations for come Computer Science, but there may also be something interest theorists other logicians. basic setting involves studying the relational structures via a resource-indexed family adjunctions ...

Agent programming languages based on the Belief, Desire and Intentions (BDI) framework present some interesting challenges for logicians. While BDI logics have been studied extensively, problems related to belief update and analysis of plans in BDI agent programming languages have received less attention.

Work on how to axiomatize the subtheories of first-order theory in which only a proper subset of their extra-logical vocabulary is being used led to a theorem on recursive axiomatizability and to an interpolation theorem for first-order logic. There were some fortuitous events and several logicians played a helpful role.

Abstract Belnap and Dunn’s well-known 4-valued logic FDE is an interesting useful non-classical logic. defined by using conjunction, disjunction negation as the sole propositional connectives. Then question of expanding with implication connective course great interest. In this sense, some implicative expansions have been proposed in literature, among which Brady’s BN4 seems to be preferred opt...

Logicians have, by and large, engaged in the convenient fiction that sentences of natural languages (at least declarative sentences) are either true or false or, at worst, lack a truth value, or have a third value often interpreted as 'nonsense'. And most contemporary linguists who have thought seriously about semantics, especially formal semantics, have largely shared this fiction, primarily f...

some contemporary logicians have introduced a new simple method of logical consequences and reduced all immediate arguments to conversion and obversion. by dint of positive and infinite terms, one of the logicians, reza akbari, increased the four traditional quantified propositions to 32 ones: the 4 well-known positives, 4 subject-infinites, 4 predicate-infinites, 4 two-sided-infinites, and the...

Van Benthem has recently remarked that Nozick’s notion of knowledge via ‘tracking the truth’ constitutes ‘[...] an open challenge’ to logicians. It is easy to see that its adoption will block laws such as Distribution or Introspection. But are there any valid inference patterns left? Given some plausible background logic of belief and counterfactuals, what is the complete set of validities of N...

Abstract A logic L has the ‘variable-sharing property’ (VSP) if in all L-theorems of form $A\rightarrow B$, $A$ and $B$ share at least a propositional variable. ‘Ackermann (AP) (B\rightarrow C)$, contains conditional connective ($\rightarrow $). Anderson Belnap consider VSP necessary property any relevant logic, both AP properties (relevant) entailment logic. Now, among logicians, Brady’s BN4 i...