``The main purpose of a programming language is to help the programmer in the practise of his art.''and its influence, quoting E.W. Dijkstra:
``A ... programming language ... influences our thinking.''He then proposed some principles for the design of declarative (programming) languages:
As for item 1, Gelfond reminded that we represent knowledge about different items, objects and relations, e.g., hierarchy of classes, causal effects of actions etc. Under this perspective, the epistemological assumptions of ASP have to be critically reviewed. Knowledge about relations between objects is given by facts and rules, which together with the semantics assumption elicit further relations.
As for item 2, Gelfond thinks that the language methodology should provide a unique translation of the important natural language constructs into their formal counterparts. As an example, he discussed different translations of the statement ``A block can not occupy different locations.''
Regarding the questions of the moderator, on Q2 Gelfond said that KR has a main role, but that design of the language and implementation should be separated. On Q3, he said that the design of inference engines is important, and on Q7, that the next ASP language should provide