#!/usr/bin/python # TBD: read about Factory Method, variable in docstring, sage documentation # move settings to sep file import os import sys import collections # import inspect import itertools as it import numpy as np import re class Config(object): def __init__(self): self.f_results = os.path.join(os.getcwd(), "results.out") # knot_formula is a schema for knots which signature function # will be calculated self.knot_formula = "[[k[0], k[1], k[3]], [-k[1], -k[3]], \ [k[2], k[3]], [-k[0], -k[2], -k[3]]]" # self.knot_formula = "[[k[0], k[1], k[2]], [k[3], k[4]], \ # [-k[0], -k[3], -k[4]], [-k[1], -k[2]]]" # self.knot_formula = "[[k[0], k[1], k[2]], [k[3]],\ # [-k[0], -k[1], -k[3]], [-k[2]]]" self.limit = 3 self.verbose = True self.verbose = False self.print_calculations_for_small_sigma = True self.print_calculations_for_small_sigma = False self.print_calculations_for_large_sigma = True self.print_calculations_for_large_sigma = False # is the ratio restriction for values in k_vector taken into account # False flag is usefull to make quick script tests self.only_slice_candidates = True self.only_slice_candidates = False self.stop_after_firts_large_sigma = True self.stop_after_firts_large_sigma = False class SignatureFunction(object): def __init__(self, values=None, counter=None): # set values of signature jumps if counter is None: counter = collections.Counter() if values is None: values = [] for jump_arg, jump in values: assert 0 <= jump_arg < 1, \ "Signature function is defined on the interval [0, 1)." counter[jump_arg] = jump self.cnt_signature_jumps = counter self.signature_jumps = collections.defaultdict(int, counter) def sum_of_absolute_values(self): return sum([abs(i) for i in self.cnt_signature_jumps.values()]) def is_zero_everywhere(self): return not any(self.signature_jumps.values()) def double_cover(self): # to read values for t^2 new_data = [] for jump_arg, jump in self.cnt_signature_jumps.items(): new_data.append((jump_arg/2, jump)) new_data.append((1/2 + jump_arg/2, jump)) t_data = [] for jump_arg, jump in self.signature_jumps.items(): t_data.append((jump_arg/2, jump)) t_data.append((1/2 + jump_arg/2, jump)) sf = SignatureFunction(values=t_data) a = SignatureFunction(values=new_data) assert a == sf return sf def square_root(self): # to read values for t^(1/2) new_data = [] for jump_arg, jump in self.signature_jumps.items(): if jump_arg < 1/2: new_data.append((2 * jump_arg, jump)) t_data = [] for jump_arg, jump in self.cnt_signature_jumps.items(): if jump_arg < 1/2: t_data.append((2 * jump_arg, jump)) sf = SignatureFunction(values=t_data) a = SignatureFunction(values=new_data) assert a == sf return sf def minus_square_root(self): # to read values for t^(1/2) counter = collections.Counter() new_data = [] for jump_arg, jump in self.cnt_signature_jumps.items(): if jump_arg >= 1/2: counter[mod_one(2 * jump_arg)] = jump new_data.append((mod_one(2 * jump_arg), jump)) t_data = [] for jump_arg, jump in self.signature_jumps.items(): if jump_arg >= 1/2: t_data.append((mod_one(2 * jump_arg), jump)) print(t_data) a = SignatureFunction(values=t_data) sf = SignatureFunction(values=new_data) sf2 = SignatureFunction(counter=counter) assert a == sf assert a == sf2 return sf def __lshift__(self, shift): # A shift of the signature functions corresponds to the rotation. return self.__rshift__(-shift) def __rshift__(self, shift): t_data = [] for jump_arg, jump in self.signature_jumps.items(): t_data.append((mod_one(jump_arg + shift), jump)) new_data = [] for jump_arg, jump in self.cnt_signature_jumps.items(): new_data.append((mod_one(jump_arg + shift), jump)) sf = SignatureFunction(values=new_data) a = SignatureFunction(values=t_data) assert a == sf return sf def __neg__(self): new_data = [] for jump_arg, jump in self.signature_jumps.items(): new_data.append((jump_arg, -jump)) a = SignatureFunction(values=new_data) counter = collections.Counter() counter.subtract(self.cnt_signature_jumps) sf = SignatureFunction(counter=counter) assert a == sf return sf # TBD short def __add__(self, other): new_data = collections.defaultdict(int) for jump_arg, jump in other.signature_jumps.items(): new_data[jump_arg] = jump + self.signature_jumps.get(jump_arg, 0) for jump_arg, jump in self.signature_jumps.items(): if jump_arg not in new_data.keys(): new_data[jump_arg] = self.signature_jumps[jump_arg] counter = copy(self.cnt_signature_jumps) counter.update(other.cnt_signature_jumps) assert collections.defaultdict(int, counter) == new_data return SignatureFunction(counter=counter) def __eq__(self, other): return self.cnt_signature_jumps == other.cnt_signature_jumps def __sub__(self, other): a = self + other.__neg__() counter = copy(self.cnt_signature_jumps) counter.subtract(other.cnt_signature_jumps) sf = SignatureFunction(counter=counter) assert a == sf return sf def __str__(self): result2 = ''.join([str(jump_arg) + ": " + str(jump) + "\n" for jump_arg, jump in sorted(self.signature_jumps.items())]) result = ''.join([str(jump_arg) + ": " + str(jump) + "\n" for jump_arg, jump in sorted(self.cnt_signature_jumps.items())]) assert result == result2 return result def __repr__(self): result2 = ''.join([str(jump_arg) + ": " + str(jump) + ", " for jump_arg, jump in sorted(self.signature_jumps.items())]) result = ''.join([str(jump_arg) + ": " + str(jump) + ", " for jump_arg, jump in sorted(self.cnt_signature_jumps.items())]) assert result == result2 return result[:-2] + "." def __call__(self, arg): # Compute the value of the signature function at the point arg. # This requires summing all signature jumps that occur before arg. arg = mod_one(arg) cnt = self.cnt_signature_jumps before_arg = [jump for jump_arg, jump in cnt.items() if jump_arg < arg] return 2 * sum(before_arg) + cnt[arg] class TorusCable(object): def __init__(self, knot_formula=None, k_vector=None, q_vector=None): # q_i = 2 * k_i + 1 if knot_formula is None: knot_formula = config.knot_formula if k_vector is None: if q_vector is None: # TBD docstring print("Please give a list of k (k_vector) or q values (q_vector).") return None else: k_vector = [(q - 1)/2 for q in q_vector] elif q_vector is None: q_vector = [2 * k + 1 for k in k_vector] self.knot_formula = knot_formula self.k_vector = k_vector self.q_vector = q_vector k = k_vector self.knot_sum = eval(knot_formula) self.knot_description = get_knot_descrption(*self.knot_sum) self.sigma_function = None # check sigma for all v = s * [a_1, a_2, a_3, a_4] for s in [1, q_4 - 1] def __is_sigma_for_vector_class_big(self, theta_vector): [a_1, a_2, a_3, a_4] = theta_vector q_4 = self.q_vector[3] for shift in range(1, q_4): shifted_theta = [(shift * a) % q_4 for a in [a_1, a_2, a_3, a_4]] sigma_v = self.__calculate_sigma(shifted_theta) if abs(sigma_v) > 5 + np.count_nonzero(shifted_theta): return True return False def is_sigma_for_vector_class_big(self, theta_vector): if self.sigma_function is None: self.sigma_function = self.__get_sigma_function() return self.__is_sigma_for_vector_class_big(theta_vector) def __get_sigma_function(self): k_1, k_2, k_3, k_4 = [abs(k) for k in self.k_vector] q_4 = 2 * k_4 + 1 ksi = 1/q_4 sigma_q_1 = get_untwisted_signature_function(k_1) sigma_q_2 = get_untwisted_signature_function(k_2) sigma_q_3 = get_untwisted_signature_function(k_3) def sigma_function(theta_vector): # "untwisted" part (Levine-Tristram signatures) a_1, a_2, a_3, a_4 = theta_vector untwisted_part = 2 * (sigma_q_2(ksi * a_1) - sigma_q_2(ksi * a_2) + sigma_q_3(ksi * a_3) - sigma_q_3(ksi * a_4) + sigma_q_1(ksi * a_1 * 2) - sigma_q_1(ksi * a_4 * 2)) # "twisted" part tp = [0, 0, 0, 0] for i, a in enumerate(theta_vector): if a: tp[i] = -q_4 + 2 * a - 2 * (a^2/q_4) twisted_part = tp[0] - tp[1] + tp[2] - tp[3] sigma_v = untwisted_part + twisted_part return sigma_v return sigma_function def calculate_sigma(self, theta_vector): if self.sigma_function is None: self.sigma_function = self.__get_sigma_function() return self.__calculate_sigma(theta_vector) def __calculate_sigma(self, theta_vector): return self.sigma_function(theta_vector) def check_combinations_in_range(self, range_list): if self.sigma_function is None: self.sigma_function = self.__get_sigma_function() large_sigma_for_all_combinations = True bad_vectors = [] good_vectors = [] q_4 = self.q_vector[-1] for vector in range_list: a_1, a_2, a_3, a_4 = vector if a_1 == a_2 == a_3 == a_4: continue if (a_1^2 - a_2^2 + a_3^2 - a_4^2) % q_4: continue if self.__is_sigma_for_vector_class_big(vector): good_vectors.append(vector) pass else: bad_vectors.append(vector) large_sigma_for_all_combinations = False return good_vectors, bad_vectors # def is_condition_for_vector_class_fulfilled(vector): # a_1, a_2, a_3, a_4 = vector # q_4 = self.q_vector[-1] # # check assumption - for results != 0 mod q_4 we stop here # if (a_1^2 - a_2^2 + a_3^2 - a_4^2) % q_4: # return None # if self.sigma_function is None: # self.sigma_function = self.__get_sigma_function() # return self.__is_sigma_for_vector_class_big(theta_vector) # searching for sigma > 5 + #(v_i != 0) def eval_cable_for_large_sigma(k_vector=None, knot_formula=None, print_results=True, verbose=None, q_vector=None): cable = TorusCable(knot_formula=knot_formula, k_vector=k_vector, q_vector=q_vector) q = cable.q_vector[-1] if verbose: print("\n\n") print(100 * "*") print("Searching for a large signature values for the cable sum: ") print(cable.knot_description) list_of_ranges = [ # all characters a_1, a_2, a_3, a_4 != 0 it.product(range(1, q), range(1, q), range(1, q), range(1, 2)), # a_1 == 0, a_2, a_3, a_4 != 0 it.product(range(1), range(1, q), range(1, q), range(1, 2)), # a_2 == 0, a_1, a_3, a_4 != 0 it.product(range(1, q), range(1), range(1, q), range(1, 2)), # a_3 == 0, a_1, a_2, a_4 != 0 it.product(range(1, q), range(1, q), range(1), range(1, 2)), # a_4 == 0, a_1, a_2, a_3 != 0 it.product(range(1, q), range(1, q), range(1, 2), range(1)), # a_1 == 0, a_2 == 0, a_3, a_4 != 0 it.product(range(1), range(1), range(1, q), range(1, 2)), # a_1 == 0, a_3 == 0, a_2, a_4 != 0 it.product(range(1), range(1, q), range(1), range(1, 2)), # a_1 == 0, a_4 == 0, a_3, a_2 != 0 it.product(range(1), range(1, q), range(1, 2), range(1)), # a_2 == 0, a_3 == 0, a_1, a_4 != 0 it.product(range(1, q), range(1), range(1), range(1, 2)), # a_2 == 0, a_4 == 0, a_1, a_3 != 0 it.product(range(1, q), range(1), range(1, 2), range(1)), # a_3 == 0, a_4 == 0, a_1, a_2 != 0 it.product(range(1, q), range(1, 2), range(1), range(1)), ] for ranges in list_of_ranges: good_vectors, bad_vectors = cable.check_combinations_in_range(ranges) print("good_vectors : bad_vectors: " + str(len(good_vectors)) +\ " : " + str(len(bad_vectors))) # # print("\ngood_vectors") # print(len(good_vectors)) # print("\nbad_vectors") # print(len(bad_vectors)) # print(bad_vectors) return None def main(arg): if arg[1]: limit = int(arg[1]) else: limit = None search_for_large_signature_value(limit=limit) # search_for_null_signature_value(limit=limit) # searching for sigma > 5 + #(v_i != 0) over given knot schema def search_for_large_signature_value(knot_formula=None, limit=None, verbose=None): if limit is None: limit = config.limit if knot_formula is None: knot_formula = config.knot_formula if verbose is None: vebose = config.verbose # number of k_i (q_i) variables to substitute k_vector_size = extract_max(knot_formula) + 1 limit = max(limit, k_vector_size) combinations = it.combinations(range(1, limit + 1), k_vector_size) P = Primes() good_knots = [] # with open(config.f_results, 'w') as f_results: # iterate over q-vector for c in combinations: k = [(P.unrank(i + 2) - 1)/2 for i in c] if config.only_slice_candidates: if not (k[3] > 4 * k[2] and k[2] > 4 * k[1] and k[1] > 4 * k[0]): if verbose: print("Ratio-condition does not hold") continue result = eval_cable_for_large_sigma(k_vector=k, knot_formula=knot_formula, print_results=False) good_knots.append(result) return good_knots def print_results_LT(v_theta, knot_description, ksi, untwisted_part, k, sigma_q_1, sigma_q_2, sigma_q_3): a_1, a_2, a_3, a_4 = v_theta k_1, k_2, k_3, k_4 = [abs(i) for i in k] print("\n\nLevine-Tristram signatures for the cable sum: ") print(knot_description) print("and characters:\n" + str(v_theta) + ",") print("ksi = " + str(ksi)) print("\n\n2 * (sigma_q_2(ksi * a_1) + " + \ "sigma_q_1(ksi * a_1 * 2) - " +\ "sigma_q_2(ksi * a_2) + " +\ "sigma_q_3(ksi * a_3) - " +\ "sigma_q_3(ksi * a_4) - " +\ "sigma_q_1(ksi * a_4 * 2))" +\ \ " = \n\n2 * (sigma_q_2(" + \ str(ksi) + " * " + str(a_1) + \ ") + sigma_q_1(" + \ str(ksi) + " * " + str(a_1) + " * 2" + \ ") - sigma_q_2(" + \ str(ksi) + " * " + str(a_2) + \ ") + sigma_q_3(" + \ str(ksi) + " * " + str(a_3) + \ ") - sigma_q_3(" + \ str(ksi) + " * " + str(a_4) + \ ") - sigma_q_1(" + \ str(ksi) + " * " + str(a_4) + " * 2)) " + \ \ " = \n\n2 * (sigma_q_2(" + \ str(mod_one(ksi * a_1)) + \ ") + sigma_q_1(" + \ str(mod_one(ksi * a_1 * 2)) + \ ") - sigma_q_2(" + \ str(mod_one(ksi * a_2)) + \ ") + sigma_q_3(" + \ str(mod_one(ksi * a_3)) + \ ") - sigma_q_3(" + \ str(mod_one(ksi * a_4)) + \ ") - sigma_q_1(" + \ str(mod_one(ksi * a_4 * 2)) + \ \ ") = \n\n2 * ((" + \ str(sigma_q_2(ksi * a_1)) + \ ") + (" + \ str(sigma_q_1(ksi * a_1 * 2)) + \ ") - (" + \ str(sigma_q_2(ksi * a_2)) + \ ") + (" + \ str(sigma_q_3(ksi * a_3)) + \ ") - (" + \ str(sigma_q_3(ksi * a_4)) + \ ") - (" + \ str(sigma_q_1(ksi * a_4 * 2)) + ")) = " + \ "\n\n2 * (" + \ str(sigma_q_2(ksi * a_1) + sigma_q_1(ksi * a_1 * 2) - sigma_q_2(ksi * a_2) + sigma_q_3(ksi * a_3) - sigma_q_3(ksi * a_4) - sigma_q_1(ksi * a_4 * 2)) + \ ") = " + str(untwisted_part)) print("\nSignatures:") print("\nq_1 = " + str(2 * k_1 + 1) + ": " + repr(sigma_q_1)) print("\nq_2 = " + str(2 * k_2 + 1) + ": " + repr(sigma_q_2)) print("\nq_3 = " + str(2 * k_3 + 1) + ": " + repr(sigma_q_3)) def print_results_sigma(v_theta, knot_description, tp, q_4): a_1, a_2, a_3, a_4 = v_theta print("\n\nSigma values for the cable sum: ") print(knot_description) print("and characters: " + str(v_theta)) print("\nsigma(T_{2, q_4}, ksi_a) = " + \ "-q + (2 * a * (q_4 - a)/q_4) " +\ "= -q + 2 * a - 2 * a^2/q_4 if a != 0,\n\t\t\t" +\ " = 0 if a == 0.") print("\nsigma(T_{2, q_4}, chi_a_1) = ", end="") if a_1: print("- (" + str(q_4) + ") + 2 * " + str(a_1) + " + " +\ "- 2 * " + str(a_1^2) + "/" + str(q_4) + \ " = " + str(tp[0])) else: print("0") print("\nsigma(T_{2, q_4}, chi_a_2) = ", end ="") if a_2: print("- (" + str(q_4) + ") + 2 * " + str(a_2) + " + " +\ "- 2 * " + str(a_2^2) + "/" + str(q_4) + \ " = " + str(tp[1])) else: print("0", end="") print("\nsigma(T_{2, q_4}, chi_a_3) = ", end="") if a_3: print("- (" + str(q_4) + ") + 2 * " + str(a_3) + " + " +\ "- 2 * " + str(a_3^2) + "/" + str(q_4) + \ " = " + str(tp[2])) else: print("0", end="") print("\nsigma(T_{2, q_4}, chi_a_4) = ", end="") if a_4: print("- (" + str(q_4) + ") + 2 * " + str(a_4) + " + " +\ "- 2 * " + str(a_4^2) + "/" + str(q_4) + \ " = " + str(tp[3])) else: print("0") print("\n\nsigma(T_{2, q_4}, chi_a_1) " + \ "- sigma(T_{2, q_4}, chi_a_2) " + \ "+ sigma(T_{2, q_4}, chi_a_3) " + \ "- sigma(T_{2, q_4}, chi_a_4) =\n" + \ "sigma(T_{2, q_4}, " + str(a_1) + \ ") - sigma(T_{2, q_4}, " + str(a_2) + \ ") + sigma(T_{2, q_4}, " + str(a_3) + \ ") - sigma(T_{2, q_4}, " + str(a_4) + ") = " + \ str(tp[0] - tp[1] + tp[2] - tp[3])) # searching for signature == 0 def search_for_null_signature_value(knot_formula=None, limit=None): if limit is None: limit = config.limit if knot_formula is None: knot_formula = config.knot_formula k_vector_size = extract_max(knot_formula) + 1 combinations = it.combinations_with_replacement(range(1, limit + 1), k_vector_size) with open(config.f_results, 'w') as f_results: for k in combinations: if config.only_slice_candidates and k_vector_size == 5: k = get_shifted_combination(k) knot_sum = eval(knot_formula) if is_trivial_combination(knot_sum): print(knot_sum) continue result = eval_cable_for_null_signature(knot_sum) if result is not None: knot_description, null_comb, all_comb = result line = (str(k) + ", " + str(null_comb) + ", " + str(all_comb) + "\n") f_results.write(line) # searching for signature == 0 def eval_cable_for_null_signature(knot_sum, print_results=False, verbose=None): # search for zero combinations if verbose is None: vebose = config.verbose f = get_signature_as_theta_function(*knot_sum, verbose=False) knot_description = get_knot_descrption(*knot_sum) all_combinations = get_number_of_combinations(*knot_sum) null_combinations = 0 zero_theta_combinations = [] range_list = [range(abs(knot[-1]) + 1) for knot in knot_sum] if verbose: print() print(knot_description) for v_theta in it.product(*range_list): if f(*v_theta, verbose=False).is_zero_everywhere(): zero_theta_combinations.append(v_theta) m = len([theta for theta in v_theta if theta != 0]) null_combinations += 2^m # else: # assert sum(v_theta) != 0 if print_results: print() print(knot_description) print("Zero cases: " + str(null_combinations)) print("All cases: " + str(all_combinations)) if zero_theta_combinations: print("Zero theta combinations: ") for el in zero_theta_combinations: print(el) if null_combinations^2 >= all_combinations: return knot_description, null_combinations, all_combinations return None def is_trivial_combination(knot_sum): # for now is applicable only for schema that are sums of 4 cables if len(knot_sum) == 4: oposit_to_first = [-k for k in knot_sum[0]] if oposit_to_first in knot_sum: return True return False def get_shifted_combination(combination): # for now applicable only for schama # "[[k[0], k[1], k[2]], [k[3], k[4]], # [-k[0], -k[3], -k[4]], [-k[1], -k[2]]]" # shift the combination so that the knot can be a candidate for slice combination = [combination[0], 4 * combination[0] + combination[1], 4 * (4 * combination[0] + combination[1]) + combination[2], 4 * combination[0] + combination[3], 4 * (4 * combination[0] + combination[3]) + combination[4]] return combination def get_blanchfield_for_pattern(k_n, theta): if theta == 0: a = get_untwisted_signature_function(k_n) return a.square_root() + a.minus_square_root() results = [] k = abs(k_n) ksi = 1/(2 * k + 1) # lambda_odd, i.e. (theta + e) % 2 != 0 for e in range(1, k + 1): if (theta + e) % 2 != 0: results.append((e * ksi, 1 * sgn(k_n))) results.append((1 - e * ksi, -1 * sgn(k_n))) # lambda_even # print("normal") for e in range(1, theta): if (theta + e) % 2 == 0: results.append((e * ksi, 1 * sgn(k_n))) results.append((1 - e * ksi, -1 * sgn(k_n))) # print("reversed") for e in range(theta + 1, k + 1): if (theta + e) % 2 != 0: continue results.append((e * ksi, -1 * sgn(k_n))) results.append((1 - e * ksi, 1 * sgn(k_n))) return SignatureFunction(values=results) def get_signature_summand_as_theta_function(*arg): def get_signture_function(theta): # TBD: another formula (for t^2) description k_n = abs(arg[-1]) if theta > k_n: msg = "k for the pattern in the cable is " + str(arg[-1]) + \ ". Parameter theta should not be larger than abs(k)." raise ValueError(msg) # twisted part cable_signature = get_blanchfield_for_pattern(arg[-1], theta) # untwisted part for i, k in enumerate(arg[:-1][::-1]): ksi = 1/(2 * k_n + 1) power = 2^i a = get_untwisted_signature_function(k) shift = theta * ksi * power b = a >> shift c = a << shift for _ in range(i): b = b.double_cover() c = c.double_cover() cable_signature += b + c test = b - c test2 = -c + b assert test == test return cable_signature get_signture_function.__doc__ = get_signture_function_docsting return get_signture_function def get_untwisted_signature_function(j): # return the signature function of the T_{2,2k+1} torus knot k = abs(j) w = ([((2 * a + 1)/(4 * k + 2), -1 * sgn(j)) for a in range(k)] + [((2 * a + 1)/(4 * k + 2), 1 * sgn(j)) for a in range(k + 1, 2 * k + 1)]) return SignatureFunction(values=w) def get_signature_as_theta_function(*arg, **key_args): if 'verbose' in key_args: verbose_default = key_args['verbose'] else: verbose_default = config.verbose def signature_as_theta_function(*thetas, **kwargs): verbose = verbose_default if 'verbose' in kwargs: verbose = kwargs['verbose'] la = len(arg) lt = len(thetas) # call with no arguments if lt == 0: return signature_as_theta_function(*(la * [0])) if lt != la: msg = "This function takes exactly " + str(la) + \ " arguments or no argument at all (" + str(lt) + " given)." raise TypeError(msg) sf = SignatureFunction() # for each cable in cable sum apply theta for i, knot in enumerate(arg): try: sf += get_signature_summand_as_theta_function(*knot)(thetas[i]) # in case wrong theata value was given except ValueError as e: print("ValueError: " + str(e.args[0]) +\ " Please change " + str(i + 1) + ". parameter.") return None if verbose: print() print(str(thetas)) print(sf) return sf signature_as_theta_function.__doc__ = signature_as_theta_function_docstring return signature_as_theta_function def get_number_of_combinations(*arg): number_of_combinations = 1 for knot in arg: number_of_combinations *= (2 * abs(knot[-1]) + 1) return number_of_combinations def extract_max(string): numbers = re.findall('\d+', string) numbers = map(int, numbers) return max(numbers) def mod_one(n): return n - floor(n) def get_knot_descrption(*arg): description = "" for knot in arg: if knot[0] < 0: description += "-" description += "T(" for k in knot: description += "2, " + str(2 * abs(k) + 1) + "; " description = description[:-2] + ") # " return description[:-3] get_blanchfield_for_pattern.__doc__ = \ """ Arguments: k_n: a number s.t. q_n = 2 * k_n + 1, where T(2, q_n) is a pattern knot for a single cable from a cable sum theta: twist/character for the cable (value form v vector) Return: SignatureFunction created for twisted signature function for a given cable and theta/character Based on: Proposition 9.8. in Twisted Blanchfield Pairing (https://arxiv.org/pdf/1809.08791.pdf) """ get_number_of_combinations.__doc__ = \ """ Arguments: arbitrary number of lists of numbers, each list encodes a single cable Return: number of possible theta values combinations that could be applied for a given cable sum, i.e. the product of q_j for j = {1,.. n}, where n is a number of direct components in the cable sum, and q_j is the last q parameter for the component (a single cable) """ get_knot_descrption.__doc__ = \ """ Arguments: arbitrary number of lists of numbers, each list encodes a single cable. Examples: sage: get_knot_descrption([1, 3], [2], [-1, -2], [-3]) 'T(2, 3; 2, 7) # T(2, 5) # -T(2, 3; 2, 5) # -T(2, 7)' """ mod_one.__doc__ = \ """ Argument: a number Return: the fractional part of the argument Examples: sage: mod_one(9 + 3/4) 3/4 sage: mod_one(-9 + 3/4) 3/4 sage: mod_one(-3/4) 1/4 """ search_for_null_signature_value.__doc__ = \ """ This function calculates signature functions for knots constracted accordinga a schema for a cable sum. The schema is given as an argument or defined in the class Config. Results of calculations will be writen to a file and the stdout. limit is the upper bound for the first value in k_vector, i.e k[0] value in a cable sum, where q_0 = 2 * k[0] + 1. (the number of knots that will be constracted depends on limit value). For each knot/cable sum the function eval_cable_for_null_signature is called. eval_cable_for_null_signature calculetes the number of all possible thetas (characters) and the number of combinations for which signature function equeles zero. In case the first number is larger than squere of the second, eval_cable_for_null_signature returns None (i.e. the knot can not be slice). Data for knots that are candidates for slice knots are saved to a file. """ extract_max.__doc__ = \ """ Return: maximum of absolute values of numbers from given string Examples: sage: extract_max("([1, 3], [2], [-1, -2], [-10])") 10 sage: extract_max("3, 55, ewewe, -42, 3300, 50") 3300 """ eval_cable_for_null_signature.__doc__ = \ """ This function calculates all possible twisted signature functions for a knot that is given as an argument. The knot should be encoded as a list of its direct component. Each component schould be presented as a list of integers. This integers correspond to the k - values in each component/ cable. If a component is a mirror image of a cable the minus sign should be written before each number for this component. For example: eval_cable_for_null_signature([[1, 8], [2], [-2, -8], [-2]]) eval_cable_for_null_signature([[1, 2], [-1, -2]]) sage: eval_cable_for_null_signature([[1, 3], [2], [-1, -2], [-3]]) T(2, 3; 2, 7) # T(2, 5) # -T(2, 3; 2, 5) # -T(2, 7) Zero cases: 1 All cases: 1225 Zero theta combinations: (0, 0, 0, 0) sage: The numbers given to the function eval_cable_for_null_signature are k-values for each component/cable in a direct sum. """ get_signature_as_theta_function.__doc__ = \ """ Function intended to construct signature function for a connected sum of multiple cables with varying theta parameter values. Accept arbitrary number of arguments (depending on number of cables in connected sum). Each argument should be given as list of integer representing k - parameters for a cable: parameters k_i (i=1,.., n-1) for satelit knots T(2, 2k_i + 1) and - the last one - k_n for a pattern knot T(2, 2k_n + 1). Returns a function that will take theta vector as an argument and return an object SignatureFunction. To calculate signature function for a cable sum and a theta values vector, use as below. sage: signature_function_generator = get_signature_as_theta_function( [1, 3], [2], [-1, -2], [-3]) sage: sf = signature_function_generator(2, 1, 2, 2) sage: print(sf) 0: 0 5/42: 1 1/7: 0 1/5: -1 7/30: -1 2/5: 1 3/7: 0 13/30: -1 19/42: -1 23/42: 1 17/30: 1 4/7: 0 3/5: -1 23/30: 1 4/5: 1 6/7: 0 37/42: -1 Or like below. sage: print(get_signature_as_theta_function([1, 3], [2], [-1, -2], [-3] )(2, 1, 2, 2)) 0: 0 1/7: 0 1/6: 0 1/5: -1 2/5: 1 3/7: 0 1/2: 0 4/7: 0 3/5: -1 4/5: 1 5/6: 0 6/7: 0 """ get_signature_summand_as_theta_function.__doc__ = \ """ Argument: n integers that encode a single cable, i.e. values of q_i for T(2,q_0; 2,q_1; ... 2, q_n) Return: a function that returns SignatureFunction for this single cable and a theta given as an argument """ SignatureFunction.__doc__ = \ """ This simple class encodes twisted and untwisted signature functions of knots. Since the signature function is entirely encoded by its signature jump, the class stores only information about signature jumps in a dictionary self.signature_jumps. The dictionary stores data of the signature jump as a key/values pair, where the key is the argument at which the functions jumps and value encodes the value of the jump. Remember that we treat signature functions as defined on the interval [0,1). """ get_signture_function_docsting = \ """ This function returns SignatureFunction for previously defined single cable T_(2, q) and a theta given as an argument. The cable was defined by calling function get_signature_summand_as_theta_function(*arg) with the cable description as an argument. It is an implementaion of the formula: Bl_theta(K'_(2, d)) = Bl_theta(T_2, d) + Bl(K')(ksi_l^(-theta) * t) + Bl(K')(ksi_l^theta * t) """ signature_as_theta_function_docstring = \ """ Arguments: Returns object of SignatureFunction class for a previously defined connected sum of len(arg) cables. Acept len(arg) arguments: for each cable one theta parameter. If call with no arguments, all theta parameters are set to be 0. """ main.__doc__ = \ """ This function is run if the script was called from the terminal. It calls another function, search_for_null_signature_value, to calculate signature functions for a schema of a cable sum defined in the class Config. Optionaly a parameter (a limit for k_0 value) can be given. Thought to be run for time consuming calculations. """ if __name__ == '__main__': global config config = Config() if '__file__' in globals(): # skiped in interactive mode as __file__ is not defined main(sys.argv) """ This script calculates signature functions for knots (cable sums). The script can be run as a sage script from the terminal or used in interactive mode. A knot (cable sum) is encoded as a list where each element (also a list) corresponds to a cable knot, e.g. a list [[1, 3], [2], [-1, -2], [-3]] encodes T(2, 3; 2, 7) # T(2, 5) # -T(2, 3; 2, 5) # -T(2, 7). To calculate the number of characters for which signature function vanish use the function eval_cable_for_null_signature as shown below. sage: eval_cable_for_null_signature([[1, 3], [2], [-1, -2], [-3]]) T(2, 3; 2, 7) # T(2, 5) # -T(2, 3; 2, 5) # -T(2, 7) Zero cases: 1 All cases: 1225 Zero theta combinations: (0, 0, 0, 0) sage: The numbers given to the function eval_cable_for_null_signature are k-values for each component/cable in a direct sum. To calculate signature function for a knot and a theta value, use function get_signature_as_theta_function (see help/docstring for details). About notation: Cables that we work with follow a schema: T(2, q_1; 2, q_2; 2, q_4) # -T(2, q_2; 2, q_4) # # T(2, q_3; 2, q_4) # -T(2, q_1; 2, q_3; 2, q_4) In knot_formula each k[i] is related with some q_i value, where q_i = 2*k[i] + 1. So we can work in the following steps: 1) choose a schema/formula by changing the value of knot_formula 2) set each q_i all or choose range in which q_i should varry 3) choose vector v / theata vector. """