# $Id: easterP.n3,v 1.12 2005/08/07 19:13:52 amdus Exp $
# original copy at http://www.w3.org/2000/10/swap/test/easter/easter.n3
#

@prefix log: <http://www.w3.org/2000/10/swap/log#>.
@prefix math: <http://www.w3.org/2000/10/swap/math#>.
@prefix str: <http://www.w3.org/2000/10/swap/string#>.
@prefix owl: <http://www.w3.org/2002/07/owl#>.
@prefix xsd: <http://www.w3.org/2001/XMLSchema#>.
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>.
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>.
@prefix : <http://www.agfa.com/w3c/euler/easterP#>.

<> rdfs:comment """
              Divide            by      Quotient  Remainder
        ---------------------------------------------------
                 y               19                   j
                 y              100        k          h
                 k                4        m          n
               k + 8             25        p
             k - p + 1            3        q
        19j + k - m - q + 15     30                   r
                 h                4        s          u
        32 + 2n + 2s - r - u      7                   v
           j + 11r + 22v        451        w
         r + v - 7w + 114        31        x          z

Here x is the number of the month ond 1 + z is the day of that
month upon which Easter Sunday falls in the year y. 
""".

2003 a :Year.
2004 a :Year.
2005 a :Year.
2006 a :Year.

{?Y a :Year.
 (?Y 19) math:remainder ?J.
 (?Y 100) math:integerQuotient ?K; math:remainder ?H.
 (?K 4) math:integerQuotient ?M; math:remainder ?N.
 ((?K 8)!math:sum 25) math:integerQuotient ?P.
 (((?K ?P)!math:difference 1)!math:sum 3) math:integerQuotient ?Q.
 ((((((19 ?J)!math:product ?K)!math:sum ?M)!math:difference
      ?Q)!math:difference 15)!math:sum 30) math:remainder ?R.
 (?H 4) math:integerQuotient ?S; math:remainder ?U.
 ((32 (2 ?N)!math:product (2 ?S)!math:product ?R!math:negation
      ?U!math:negation)!math:sum 7) math:remainder ?V.
 ((?J (11 ?R)!math:product (22 ?V)!math:product)!math:sum 451)
      math:integerQuotient ?W.
 ((?R ?V (7 ?W)!math:product!math:negation 114)!math:sum 31)
      math:integerQuotient ?X; math:remainder ?Z.
 (?Z 1) math:sum ?DAY.
} => {
 ?Y :hasEasterOnDay ?DAY; :hasEasterOnMonth ?X
}.