captioning sponsored by wnet >> sreenivasan: on this edition for sunday, may 24th: new criticism from the obama administration that iraqi forces showed "no will to fight" for ramadi. and in our signature segment, colorado's legalization of marijuana has angered some neighboring states. now they're suing. >> it's still illegal here. we don't have a choice. we have to enforce the law. >> sreenivasan: and some perspective on the death of a nobel prize winning mathematician. next on pbs newshour weekend. >> pbs newshour weekend is made possible by:

corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we are your retirement company. additional support is provided by: and by the corporation for public broadcasting and by contributions to your pbs station from viewers like you. thank you. from the tisch wnet studios in lincoln center in new york, hari sreenivasan. >> sreenivasan: good evening thanks for joining us. new criticism of iraqi troops is casting doubt on whether they can actually beat back isis in major cities. the u.s. secretary of defense commented for the first time since militants took the city of ramadi, telling c.n.n. that iraqi forces pulled back even though they vastly outnumbered the isis fighters. >> what apparently happened was that the iraqi forces just showed no will to fight. air-strikes are effective, but neither they nor anything they do can substitute for the iraqi forces will to fight.

they are they ones who have to beat isil. >> sreenivasan: some 3,000 u.s. military personnel are serving in non-combat areas, right now restricted to training iraqi fighters. however, senator john mccain told cbs' "face the nation" he wants to send thousands more american troops to join the fight against isis. >> forward air controllers special forces, training, equipping. right now it's shia militia, the same ones that we fought against during the surge that are now doing the fighting. >> sreenivasan: meanwhile, isis is gaining ground in syria. government t.v. reports militants killed at least 400 people in palmyra, including women and children. the isis flag is flying over the city's ancient ruins. in cleveland, the police chief says demonstrators will be allowed to march during tonight's nba playoff game at quicken loans arena, as long as the protests remain peaceful.

yesterday's protests were mostly peaceful immediately following the acquittal of police officer michael brelo. but by the end of the night, police had arrested 71 demonstrators, some of whom were accused of assaulting innocent bystanders. the protests began after officer brelo was cleared of all charges in the shooting deaths of two unarmed black suspects. negotiators are claiming they've made progress during intense talks over iran's nuclear program. but iran's leaders might not agree. iran's deputy foreign minister said on state-tv that iran has agreed to allow united nations inspectors "managed access" to military sites. that means inspectors will only be allowed to take environmental samples near those areas. but that contradicts what iran's supreme leader said about the talks last week. he vowed not to allow any foreign access. iran's top military leaders also refused to comply with such demands. in malaysia, authorities have reportedly found as many as thirty mass graves, possibly filled with the bodies of hundreds of migrants. other mass graves were found

earlier this month-- most near suspected human trafficking camps across the thai border. off the coast, thousands of migrants are still reportedly stranded at sea. today, pope francis encouraged the international community to provide humanitarian assistance. in central nepal, thousands of villagers are being told to get to higher ground. officials fear a landslide that blocked a major river could eventually trigger a devastating flood for miles downstream. the landslide created a natural dam, and the river has started to overflow its banks. this is just the latest landslide following the 7.8 magnitude earthquake that hit the region almost a month ago. more financial trouble in greece, where the minister of the interior says the country will not be able to make the next payment on its massive debt to the international monetary fund. greece was supposed to send the i.m.f. 1.6 billion euros next month to pay back its 2011 bail out. if leaders cannot negotiate a new payoff deal, greece could be forced to leave the euro and go

back to the drachma-- potentially throwing the country into bankruptcy. in central texas, dangerous weather and flash floods have forced about 1,000 people to evacuate. rescue crews used boats to pull people to safety along the blanco river about 40 miles southwest of austin. hundreds of nearby homes are reportedly damaged. some parts of texas have gotten as much as ten inches of rain in just the past 24 hours. tonight, officials are opening emergency shelters and imposing a curfew to keep drivers off flooded roads. the pipeline that spilled thousands of gallons of crude oil off the california coast did not have an automatic shut-off valve. the associated press reports the pipe was the only one of its kind in santa barbara county that was not required to have an automatic shut off valve. the pipeline's original owner fought the county in court back in the 80's, to avoid adding the safety valve-- and won. federal regulators are still investigating the cause of the spill. the nobel prize winning mathematician whose life story was the subject of the academy award winning film "a beautiful mind" died yesterday in a taxi accident. john nash became known for his

analysis of modern "game theory." he had been diagnosed with schizophrenia in the late 50's. nash 86 and his wife alicia 82 died when their cab hit a guardrail on the new jersey turnpike. we'll have more on the life of john nash later in the program. returning to the growing fight against isis, now spreading into saudi arabia. yesterday, the islamic militant group claimed responsibility for the suicide bombing at a mosque friday. at least 21 people were killed and today the saudi king vowed to punish those involved. washington post reporter erin cunningham joins me via skype from cairo. so there has been a handful of other ins ghents the saudi kingdom over the past six months how have the authorities connected the dots? >> well, they think that you have a number of saudis that have gone to iraq and syria to participate in the insurgencies there and i think this is how

the islamic state works. they recruit people inside the various countries, and either to carry out attacks or to come back to iraq and syria and join them where they are fighting so i think the saudis were able to see this, that these people who carried out these attacks over the past six months have had contact with the islamic state and that's how they are going to identify them. >> sreenivasan: put this in perspective for us. this comes in the context of sunni shy a. shia attention that already exists in saudi arabia. >> yes there sashi a minority in eastern saudi arabia that long said they suffer from neglect from the government and also sort of sectarian insightment from the clergy inside saudi arabia so there is already this sort of festering tension between the shia and the government and i think this the something that, this is something that might make this worse certainly. >> sreenivasan: is this

something to try to fire up the shia base to try to the top it will sunni kingdom from inside? >> i i am not sure if that is something that the islamic state would be interested in doing or if they have the skills or the intelligence to do something like that but i believe that as long as there are tensions, as long as people inside saudi arabia and the government are afraid of iranian state attacks then that works to their advantage. >> sreenivasan: and of course this is the site of two of islam's most holy cities, medina, and you can't have a caliphate without those two very important sites. >> absolutely. i mean, it is very symbolic and very important. i mean even al qaeda had saudi arabia as a primary target for their own attacks. so i think that if the islamic state can carry out attacks in saudi arabia certainly they will because it is a propaganda

victory for them even if they can't get inside to take territory. >> sreenivasan: all right erin cunningham of the washington post join us via skype from cairo tonight. thanks so much. >> thank you. returning now to the death of nobel prize winning mathematician john nash. i'm joined by nash's colleague and friend, robbert dijkgraaf, director of the institute for advanced study in new jersey. >> sreenivasan: so first off my condolences to you. what are you going to miss most about your colleague and friend? >> oh joe nash was such a presence here in princeton, it is a small community and he was a genius of a different kind, somebody who totally transformed mathematics, but programs most important he was such a gentle and modest man, a great inspiration i think for all mathematicians, scientists and human beings. >> sreenivasan: what was it

about his genius that inspired generations of mathematicians what made him, him? >> well, i think many scientists and mathematicians they try to kind of climb a mountain that is somewhere out there and there is a path, although it might be very difficult, john nash was a mathematician who just picked his own mountains and produced results that nobody expected, that actually many people thought were impossible, and in that sense he opened up entirely new worlds it could have been in economics, it could have been in very abstract mathematics and geometry. he really kind of touched so many different fields. >> sreenivasan: so help somebody in the television audience understand kind of the long-term impact of john nash's work on game theory or how it affects our lives today. >> john nash basically proved that if you have a complicated game, as complicated as it can be with many players with very

many different strategies there is always kind of an optimal form where basically everybody gets the result at best as they can get and actually this is very interesting mathematically that it exists but it is used everywhere. it is used when there are live auctions, whether it is selling goods or selling, it is basically underlying all of mathematical economical theory at this moment, and it is kind of amazing that somebody who had a pure mathematical mind was able to solve this problem in such and had such enormous impacts on our lives. >> sreenivasan: people who have seen a beautiful mind or haggled for a price understand his impact on game theory, kind of math tieing our decision making but he was actually on his way back during this accident from an even bigger mathematical prize so he was still .. accomplishing feats feats that most of us have never heard about. >> yes, as i said he was the

only mathematician .. to win the nobel prize. he just won the abbel prize which is really an award that recognizes -- i think it is very important to realize that he was a very bold mathematician, who had this kind of unique ability to touch both our ordinary lives through his work in game theory but also a very very deep mathematical problems thinking about spaces and arbitrary number of dimensions, thinking about the equations, very difficult differential equations that also govern large parts of our world. he had, in that sense, i think that the recognition of his almost universal mathematical talent came at this moment. however, it is unfortunate his passing is, i am very happy that he got his recognition as one of the great estimate petitions, mathematicians of our time. >> sreenivasan: and also mere the end of his life his advocacy on behalf of mental illness

which i think will be part of his legacy. >> yes. and such an uplifting story. i mean, here, we have seen of course through many decades and also in his difficult periods and he was always around and the fact that somebody who can kind of pushes his own intellect so far, more than anybody could possibly go, and then kind of climbs back and recovers, and though it is really kind of a great a drama, but it is also a very uplifting story and i think there were, the mental health will be recognized and will be remembered and a great inspiration to many of us. >> sreenivasan: robbert dijkgraaf from the advanced mathematics at princeton, thanks for joining us. >> thank you. >> >> sreenivasan: and now to our signature segment. colorado has collected tens of

millions of dollars in tax revenues since it legalized marijuana. to many, the economic benefit is clear. but in some neighboring states, the pot policy is actually costing them money-- so they're taking their case to court. this updated story originally aired in february. alison stewart reports from nebraska. >> reporter: adam hayward is the sheriff of deuel county, nebraska, which is right by the state line with colorado. sheriff hayward says his work hasn't been the same since colorado legalized recreational marijuana. >> keep it over there. it's still illegal here. we don't have a choice. we have to enforce the law. >> reporter: the sheriff says he's arrested all sorts of people carrying marijuana back from colorado along interstate 76: teenagers making weekend runs to denver and once a 67 year old grandmother. with each arrest the sheriff collects more and more marijuana. it is cataloged and then stored in the deuel county jail cell.

>> now we keep our evidence here. >> reporter: which you can smell. >> yes. >> reporter: the sheriff says that batch of pot came from a marijuana growing facility in colorado. he's also recovered lots of edible products in cars he pulls over on i-76. the number of marijuana cases is soaring. in 2011 when colorado only sold medical cannabis, the sheriff stopped someone coming back from colorado with pot less than once a week. last year when recreational cannabis became legal, the sheriff's county had more than one marijuana case a week. earlier this year, there were at least five cases a week. >> we just go out and stop cars for normal traffic violations. and it seems to be that there are so many people that are going over to get this you just can't help but run into it just by stopping a few cars. >> reporter: what hasn't changed is the number of officers working in deuel county: three full time and two part time officers. the sheriff says his county is being stretched thin. >> well, we're a small department. we usually have one person on at

a time. so if they run across something then they're having to call somebody out. well, then you're paying overtime, and where we've had more arrests and more people in jail, you know, it takes more time in the court. you know, we're having to transport prisoners back and forth, have more people in the courtroom for security. so it ties up our time dealing with these versus, you know, we could be doing other things patrolling in town. >> reporter: it takes up time and money. after an arrest, regardless of whether the person is from nebraska, colorado or elsewhere, the county picks up the bill for housing and medical treatment for those in custody as well as the cost of hiring a public defender. sheriff hayward says his annual jail budget has almost tripled- up nearly $100,000 since 2011. >> when you have something jump up $100,000, that's a pretty big increase for 2,000 people to cover. >> reporter: how are you closing that gap financially? >> basically out here, i mean all the tax revenue is generated from property taxes. so if the county needs more money they have to raise the

property taxes, and, you know it goes back to the taxpayers. >> reporter: nebraska law ends here at the colorado border. so while sheriff hayward is doing his job just over there in the cornhusker state, over here the owner of the first dispensary by colorado's north border is doing his. >> i'm currently employing nine people full time. >> reporter: mike kollartis owns a marijuana dispensary in sedgwick, colorado, a town about seven miles from the border. his store, sedgwick alternative relief, which sells both medical and recreational marijuana, is newly renovated. it stands out along this main street that has seen better days. it has become the main draw to this quiet town of 150 people. >> they're pretty happy about the renovations i've done, the employment i've brought, the dollars, the tax revenue dollars are outstanding. >> oh my goodness. it's been good. >> reporter: lupe pena casias owns a restaurant and inn across the street. she says the town has seen a

huge financial boost because each time there's a marijuana sale at the store, the town of sedgwick gets a five dollar transaction fee. and as long as the dispensary is open, the customers keep coming. >> it's busy, busy, busy over there and busy, busy, busy here. >> reporter: employees at the store are trained to look out for customers who might break the law. the dispensary also displays signs detailing the marijuana laws of colorado and neighboring states. yet there is still an influx of pot coming into nebraska and oklahoma. so the attorneys general of both states filed a lawsuit in the u.s. supreme court in december, alleging that they, "have suffered direct and significant harm arising from the increased presence of colorado-sourced marijuana." nebraska and oklahoma also contend that colorado's marijuana law "directly conflicts with federal law and undermines the area of drug control and enforcement." and so both states are asking the supreme court to declare colorado's marijuana law unconstitutional and in doing so undo colorado's marijuana

regulatory system. but this past march, colorado asked the supreme court to drop the lawsuit. washington and oregon- states that also legalized the possession and sale of marijuana, immediately came out in support of colorado's request. the supreme court has yet to decide whether to take up the case. bill kelly is a reporter with nebraska's public radio station n.e.t. who's been covering the issue. we video chatted with him because he's based in the state's capitol lincoln, over 300 miles away from where we were reporting at the nebraska/colorado border. medical marijuana, obviously has been around for a long time in colorado, and everyone saw that recreational was coming down the pipeline. why didn't nebraska legislators get more involved in dealing with this porous border issue earlier? >> i'm not certain nebraska policy makers were really prepared for what was going to happen. you were starting to see more

possession cases, you were starting to see more driving under the influence cases. but there was, i think, a little bit of the deer-in-the- headlights feeling that we don't know what the appropriate response is. >> reporter: some nebraskan lawmakers believe that the appropriate response is to change the state's marijuana laws. but there are many different ideas about what to do: one would be to legalize medical cannabis while another would increase the fines for edible marijuana products. the penalties in nebraska depend on how much pot is in your possession. a first time offense, under an ounce, is a $300 fine. more than an ounce but less than a pound is a misdemeanor with possible jail time and a fine. but more than a pound is a felony with a maximum five years in prison and or a $10,000 fine. while nebraska deliberates whether to allow marijuana or keep it out of the state, some residents like jeremy crary find themselves caught between the laws of nebraska and colorado.

nine years ago crary accidently shot himself in the head while playing with a gun. after painful surgeries and physical therapy, he spent years on more than a dozen medications and received regular shots of botox for severe muscle spasms but recently he started taking medical cannabis instead. he says it's the most effective in relieving his pain and spasms. >> i just quit taking all my pain pills they prescribed me and stuff. >> reporter: crary has made several trips across the border to marijuana dispensaries. he says the strains of marijuana he can legally purchase in colorado are better for his pain than what he can get illegally in his area. what's it like for you to knowingly break the law when you're driving back from colorado with some weed in your car heading home? >> i mean, it makes you feel like a criminal. i hate it. i never know whether the next cop's gonna be so i'm always looking around. >> reporter: we spoke to a sheriff of deuel county which is one of those counties you have to drive through to get back this way.

are you concerned at all about being part of that group that's breaking the law or that's causing him and taxpayers in that town a problem? >> no, not really. >> reporter: why not? >> i'm not looking to just get high. i'm not trying to bring it back and sell it. i'm just trying to relieve myself of having to use pharmaceuticals to have a decent life. >> reporter: if people are making the effort to actually go buy this legally in colorado as opposed to breaking two laws in nebraska, "i'm gonna buy it illegally and then i'm gonna use it illegally." shouldn't there be some sort of elasticity to the punishment? >> no, i mean, it's legal over there. that's fine. if you wanna buy it over there, use it over there. don't come back here with it because it's illegal. >> reporter: the sheriff says he's seeing more d.u.i.d.'s- driving under the influence of drugs. he's also been visiting local schools with confiscated marijuana edibles to show teachers what students might possess. and he expects he'll spend more time on interstate 76 until this

unintended consequence is resolved. >> sreenivasan: in china, the cost of renting or buying a home in beijing is so high that many low-wage workers have been forced to live underground. their living spaces-- in tunnels, basements and old air raid shelters often lack fresh air and sunlight. those who inhabit these places make up the so-called "rat tribe". i.t.n.'s china correspondent lucy watson reports. >> so this is the pipe and this is where my wife and i sleep, he tells me. they are the underground basement -- the dark, dank tunnels, and old passageways than twist underneath china's capital. >> it is an existence of filth and darkness. they have no running water. she is a rubbish collector his wife a cleaner. his son, a delivery boy.

this is a kitchen a dining room and a bedroom. the whole family's rent costs 80 pounds a month. >> my hometown, most people are farmers but my generation wants a better future so i am here to try. i wish the government will help us but it is hopeless. >> reporter: around 20,000 of these shelters exist in beijing and they are illegal, but the authorities turn a blind eye to the problem because there is nowhere else for these people to live, yet their lower paid work is needed here. itv news also gained access to former bomb shelters, thousands live in them and landlords still operate them and -- those who form the backbone of beijing's economy. he works the streets by day, but are forced beneath them at night.

itv news beijing. >> >> sreenivasan: before we leave you tonight actress and comedian anna mirra has died at the age of 85, she is survived by her husband and comedy partner jerry stiller and her son actor ben stiller. currently on the newshour website, a navy veteran who skydives with veterans from every u.s. war since world war ii, to raise awareness for combat burn victims. on the newshour broadcast tomorrow on memorial day some perspectives on afghanistan, america's longest war, plus a look at how the war there and in iraq impact military families back on the home front. i am hari sreenivasan. thanks for watching. >> captioning sponsored by wnet captioned by media access group at wgbh access.wgbh.org

>> pbs newshour weekend is made possible by: corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we are your retirement company. additional support is provided by: and by the corporation for public broadcasting and by contributions to your pbs station from viewers like you. thank you.

♪ [singing] ♪ announcer: the stars of film, t.v. music and comedy come together at the kennedy center to celebrate the people who help our veterans. it's the 2015 lincoln awards! the lincoln awards are presen ted by the friars club, through its foundation. national broadcast funding for "the lincoln awards: a concert for veterans and the military family" is provided by leonard a. wilf and by william f. austin. mr. baldwin: as the civil war ended 150 years ago, president abraham lincoln delivered his second inaugural address ending with words that resonate to this day. "let us strive on to finish the work we are in, to bind up the nation's wounds to care for him who shall have borne the battle and for his widow and his oprhan."