dlvhex

Online Demo

This online demo of the dlvhex system allows for evaluating programs without local installation. This is intended mainly for testing and learning purposes. External sources for the program at the top may be directly implemented in a Python script below.

Please check out the predefined examples at the upper right corner for a quick overview or consider the links to the system documentation in the right-hand menu for a more detailed description.

(The online demo is currently offline)

Input

Load example:

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HEX-Program:

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External Source Definition (Python):

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import dlvhex

# concat has one input parameter of type tuple (=arbitrarily many constants),
# which specifies the terms to be concatenated
def concat(tup):
	# start with empty string and append all input constants in sequence
	ret = ""
	for x in tup:
		ret = ret + x.value()

# output the final string
	dlvhex.output((ret, ))

# computes the set of all elements in the extension
# of unary predicate p but not in that of q
def setdiff(p,q):
	# for all input atoms (over p or q)
	for x in dlvhex.getTrueInputAtoms():
		# check if the predicate is p
		if x.tuple()[0] == p:
			# check if the atom with predicate
			# being changed to q is NOT in the input
			if dlvhex.isFalse(dlvhex.storeAtom((q, x.tuple()[1]))):
				# then the element is in the output
				dlvhex.output((x.tuple()[1], ));

# register all external atoms
def register():
	# setdiff has two predicate input parametrers and its output arity is 1
	dlvhex.addAtom("setdiff", (dlvhex.PREDICATE, dlvhex.PREDICATE), 1)
	# concat has arbitrarily many input parameters
	# of type constant (=TUPLE) and its output arity is 1
	dlvhex.addAtom("concat", (dlvhex.TUPLE, ), 1)

Command-line Options:

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Filter predicates (comma-separated):
Number of answer sets to compute (empty or 0 means all):
Allow strong negation:
Liberal safety:
Custom options:

Output

Please prepare your input and click 'Evaluate' to run the reasoner

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dlvhex source code @ github.com
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