This is a Python script for computing the strong paradigm for Icelandic 'kaldur' ('cold') given the toy analysis presented in Drummond & Hornstein (forthcoming).

kaldur.py

# coding=utf-8
import sys
from itertools import *
from sets import *

vocab_items = [(x[0], Set(x[1])) for x in
    (u'kalt', ()),
    (u'kaldur', ('+A', '+B')),
    (u'köld', ('-B',)),
    (u'kaldan', ('-pl', '+acc', '+A', '+B')),
    (u'kalda', ('-pl', '+acc', '+A', '-B')),
    (u'köldum', ('+dat', '+A', '+B')),
    (u'kaldri', ('-pl', '+dat', '-B')),
    (u'köldu', ('+dat', '-A', '+B')),
    (u'kaldrar', ('-pl', '+gen', '-B')),
    (u'kalds', ('-pl', '+gen', '+A', '+B')),
    (u'kaldir', ('+pl', '+A', '+B')),
    (u'kaldar', ('+pl', '+A', '-B')),
    (u'kaldra', ('+pl', '+gen', '+A', '-B')),
]

impoverishment_rules = [(Set(x[0]), Set(x[1])) for x in
    (('+gen',), ('+A',)),
    (('+pl', '+gen'), ('-B',)),
    (('+pl', '-A'), ('-B',)),
    (('+pl', '+dat'), ('+A', '+B', '-pl')),
    (('+pl', '+acc', '+B'), ('-pl', '-B'))
]

def proper_subset(specification1, specification2):
    left = False
    right = False
    for x in specification1:
        if x not in specification2:
            left = True
            break
    for x in specification2:
        if x not in specification1:
            right = True
            break
    return right and not left

def check_match(specification, item):
    for f in specification:
        if f not in item:
            return False
    return True

def apply_impoverishment_rule(rule, item_specification):
    item_specification = [x for x in item_specification]
    applied = False
    if check_match(rule[0], item_specification):
        applied = True
        for f in rule[1]:
            ff = (f[0] == '+' and '-' or '+') + f[1:]
            if ff in item_specification:
                i = item_specification.index(ff)
                item_specification[i] = f
            elif f not in item_specification:
                item_specification.add(f)
    return tuple(item_specification), applied

def filter_by_order(vocab_items):
    lattice_levels = [[vocab_items[0]]]
    for it in islice(vocab_items, 1, None):
        inserted = False
        for j in xrange(len(lattice_levels)):
            if proper_subset(it[1], lattice_levels[j][0]):
                inserted = True
                if j == 0:
                    lattice_levels.insert(0, [it])
                else:
                    lattice_levels[j-1].append(it)
                break
        if not inserted:
            for it2 in lattice_levels[-1]:
                if proper_subset(it2[1], it[1]):
                    inserted = True
                    lattice_levels.append([it])
                    break
            if not inserted:
                lattice_levels[-1].append(it)

    return lattice_levels[-1]

def execute(impoverishment_rules, vocab_items, item_specification):
    for r in impoverishment_rules:
        item_specification, applied = apply_impoverishment_rule(r, item_specification)

    matching = filter_by_order([x for x in vocab_items if check_match(x[1], item_specification)])
    if len(matching) > 1:
        print "\n\nAmbiguity:", matching
        return None, False
    if len(matching) == 0:
        return None, False

    return matching[0], True

def print_icelandic_table():
    for pl in [['-pl'], ['+pl']]:
        print (pl[0][0] == '-' and "[Singular]" or "[Plural]  ") + " MASC       FEM        NEUTER"
        for case in [['+nom'], ['+acc'], ['+dat'], ['+gen']]:
            sys.stdout.write(case[0][1:].upper() + (" " * (11-len(case[0][1:]))))
            
            for gender in [('masc', ['+A', '+B']), ('fem', ['+A', '-B']), ('neuter', ['-A', '+B'])]:
                fs = [x for x in pl]
                fs.extend(gender[1])
                fs.extend(case)
                fs = tuple(fs)

                x, ok = execute(impoverishment_rules, vocab_items, fs)
                if not ok:
                    return
                sys.stdout.write(x[0])
                if gender[0] != 'neuter':
                    sys.stdout.write(" " * (11-len(x[0])))
                else:
                    print
        print

print_icelandic_table()